It also uses a questionable definition of "newbie": user accounts that are in the most recently-created 1% (i.e. whose user ID is greater than 0.99*highestUserID)

Other options are (a) move it to an extension and (b) kill it entirely. Willing to be steered.

Just to explicitly state its current label – “Show contributions of new accounts only” option should be considered to be removed?

In T220447#5095926, @Volker_E wrote:

Just to explicitly state its current label – “Show contributions of new accounts only” option should be considered to be removed?

That's what I'm proposing, yes.

Special:DeletedContributions and Special:NewFiles also have this option

The proposal to remove the option “Show contributions of new accounts only” from Special:Contributions is not a good idea Special:Contributions&contribs=newbie&target=newbies is the most convenient way to check the edits of new editors and is more convenient to access than Recent Changes. If the functionality is split out into it's own function then fine but removal without replacement is unacceptable.

In T220447#5191861, @Nthep wrote:

[..] Special:Contributions&target=newbies is [..] more convenient to access than Recent Changes.

Can you elaborate in what way Newbie Contribs is more convenient than RC? Do you think it is possible for Recent Changes to become more convenient?

The main reason the Special:Contributions feature is a problem is its performance. It is very slow to load because Contributions (unlike RC) has no time limit. You can go to page 3,000 to find older edits (in theory). The Contributions database is designed for "View history" (for a single page only) and "User contribs" (for a single user only). The Newbies query is an unlimited search for all revisions by many different users, which is hard to optimise. But, we (humans) know that it is unlikely for a new user to have made edits 10 years ago, or to have more than a million edits. But, in theory that is possible because there is no time limit on "newest 1% of users". The database does not know this :)

To make these queries fast, we need to limit it by time (e.g. 30 days), and have a more specific meaning of "new user" (e.g. registered in last N days, with upto N edits).

And... that's exactly what recent changes now does. The Recent changes database is like the Contribs database, but limited to 30 days, with fast replicas optimised for arbitrary searches by any page or user. And the "newcomer" filter in recent changes shows edits by users registered in the last N days with upto N edits. (For en.wikipedia.org, it is currently set to <= 4 days and <= 10 edits).

In T220447#5388610, @Krinkle wrote:

In T220447#5191861, @Nthep wrote:

[..] Special:Contributions&target=newbies is [..] more convenient to access than Recent Changes.

Can you elaborate in what way Newbie Contribs is more convenient than RC? Do you think it is possible for Recent Changes to become more convenient?

The main reason the Special:Contributions feature is a problem is its performance. It is very slow to load because Contributions (unlike RC) has no time limit. You can go to page 3,000 to find older edits (in theory). The Contributions database is designed for "View history" (for a single page only) and "User contribs" (for a single user only). The Newbies query is an unlimited search for all revisions by many different users, which is hard to optimise. But, we (humans) know that it is unlikely for a new user to have made edits 10 years ago, or to have more than a million edits. But, in theory that is possible because there is no time limit on "newest 1% of users". The database does not know this :)

To make these queries fast, we need to limit it by time (e.g. 30 days), and have a more specific meaning of "new user" (e.g. registered in last N days, with upto N edits).

And... that's exactly what recent changes now does. The Recent changes database is like the Contribs database, but limited to 30 days, with fast replicas optimised for arbitrary searches by any page or user. And the "newcomer" filter in recent changes shows edits by users registered in the last N days with upto N edits. (For en.wikipedia.org, it is currently set to <= 4 days and <= 10 edits).

Well since I made my original comment it appears changes i.e more filters have been made to RC that make it more usable, the filter for page edits for one. Before the RC list was filled with category changes rather than edits to category pages, now these can be filtered out is a plus. If possible problematic edits can be highlighted as is available under SpecContrib via https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-rc then I think most of my concerns are gone.

Change 527624 had a related patch set uploaded (by Jforrester; owner: Jforrester):
[mediawiki/core@master] Special:Contributions: Drop 'newbies' feature

https://gerrit.wikimedia.org/r/527624

Change 527624 had a related patch set uploaded (by Catrope; owner: Jforrester):
[mediawiki/core@master] Special:Contributions: Drop 'newbies' feature

https://gerrit.wikimedia.org/r/527624

Change 527624 merged by jenkins-bot:
[mediawiki/core@master] Special:Contributions: Drop 'newbies' feature

https://gerrit.wikimedia.org/r/527624

Change 533317 had a related patch set uploaded (by DannyS712; owner: DannyS712):
[mediawiki/extensions/ArticleFeedbackv5@master] Remove newbie feature, removed in core

https://gerrit.wikimedia.org/r/533317

Change 533325 had a related patch set uploaded (by DannyS712; owner: DannyS712):
[mediawiki/core@master] Revert "ContribsPage: bring back getContribs() method"

https://gerrit.wikimedia.org/r/533325

Change 533317 merged by jenkins-bot:
[mediawiki/extensions/ArticleFeedbackv5@master] Remove newbie feature, removed in core

https://gerrit.wikimedia.org/r/533317

Change 533325 merged by jenkins-bot:
[mediawiki/core@master] ContribsPage: Re-remove the getContribs() method

https://gerrit.wikimedia.org/r/533325

For the records (as this came as a surprise to some folks): This change was announced in https://meta.wikimedia.org/wiki/Tech/News/2019/34 :

Special:Contributions/newbies will no longer be working. This is because of performance reasons. It showed edits by new accounts. You can see this in the recent changes feed instead.

It's possible to add tags to edits from "new" accounts (with whatever definition you want for "new") using Extension:AbuseFilter. For example, this filter would match all edits made by accounts with fewer than 10 edits and less than 4 days old (i.e. the current autoconfirmed cutoffs for en.WP), allowing a tag to be added to them:

user_age > 0 & 
( (int(user_editcount) < 10) | (user_age < 259200) ) &
!(action contains "createaccount")

...though note that this comes with no endorsement of being a good idea.