This is tangentially related to T52182. If I want to center a template parameter value, it should be straightforward for an editor to select it, cut it, insert Template:Center, and then past the template parameter value into the nested template. Instead, once I am inside the template parameter value editing box, I lose access to the template insertion menu. That encourages the use of obsolete methods.

Until T52182 is resolved I think it's not VisualEditor's responsibility to censor the input the user passes to a template parameter.

In T365656#9824144, @Pppery wrote:

Until T52182 is resolved I think it's not VisualEditor's responsibility to censor the input the user passes to a template parameter.

Since editors are inserting raw wikitext, they could just as easily insert a template like {center} rather than obsolete tags. Resolving T52182 would make it easier, but I don't see it as blocking this task.

It doesn't technically block this task. It's my personal opinion that this shouldn't be done on general principles that would cease to be relevant once that task is done. That opinion is of no weight since I'm not a VisualEditor developer and would not be the one writing the code to do this even if I agreed with you.

I'm inclined to say that VE shouldn't meddle with parameters inside the template editor that've been provided by a user in plain text. If we want that to happen, we should go all-in and have type="content" params (which are currently displayed as a textarea that you put wikitext into) instead display as an embedded VisualEditor (like we do for e.g. gallery descriptions).

Note that this wouldn't have affected the specific edit complained about in the task, because infobox_order hasn't assigned templatedata types to any of its paramaters, so we don't know anything about how to treat them. 🤷🏻

We prevent the addition of obsolete tags to user signatures. Why not elsewhere? Other editors are just going to have to fix them eventually. We are making work for ourselves by allowing these new errors to be created.