Feature summary (what you would like to be able to do and where):
in wikis other than enwiki, account-creation-date should not be limited to any date. If you can't get the date, then take the date of the first edit

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
some enwiki user with date:
https://en.wikipedia.org/w/index.php?title=Special%3AContributions&target=AxelBoldt&namespace=all&tagfilter=&start=&end=&limit=50
"A user with 44,480 edits. Account created on 26 July 2001."

vs:
https://ru.wikipedia.org/wiki/Категория:Википедия:Участники_со_стажем_более_21_года?uselang=en
https://ru.wikipedia.org/wiki/Special%3AContributions/Theta682?uselang=en
"A user with 649 edits."
"19:49, 26 December 2002 diff hist +72‎ N Обсуждение участника:Theta682 No edit summary thank"

first user with date:
https://ru.wikipedia.org/w/index.php?title=Special:Log&day=22&page=&subtype=&tagfilter=&type=newusers&user=&wpFormIdentifier=logeventslist&wpdate=2005-12-22&month=12&year=2005&dir=prev&offset=20051220232453|22618&uselang=en
"09:51, 22 December 2005 User account Geos (usurped) talk contribs was created "
https://ru.wikipedia.org/wiki/Special%3AContributions/Geos_(usurped)?uselang=en
"A user with 0 edits. Account created on 22 December 2005."

Benefits (why should this be implemented?):
it was originally intended that the date on the contribution page would show the contribution start date for navigation in the contribution history on the same page. It should work as originally intended