User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-43826407-20210119102940/@comment-1038387-20210119113756

This was apparently a deliberate design choice. The masthead was just replaced with the mobile bio for a reason that escapes me and probably wouldn't be sufficient anyway. The new user profiles seem to be mostly based on old Gamepedia rather than vanilla MediaWiki. Love it or hate it; it's not related to the larger matter of the necessety of updating.

Date of "joining" isn't technically correct; you can't join a wiki. Many people lurk for ages before making their first edit. But while first edit is not the most accurate metric, it's definitely less creepy than "first time you visited the wiki" in terms of privacy.