User blog comment:CowardousShiner/Petition against UCP/@comment-45914495-20200531121335/@comment-33612736-20200601081642

Devil's advocate: It's a utopia — they cannot just change heavily modified MediaWiki 1.19 to vanilla 1.33, because a lot of features will not work... at all.

Fandom is trying to rebuild most used ones using new codebase, but they won't port everything. Forum and features based on its code (message walls, comments) was marked as deprecated a long time before UCP.

Porting Forum to UCP is like porting MS-DOS to ARM — it's possible to refactor old code, but why? Discussions works on new platform with only slight modifications.

To sum up, Fandom needs to modernize even if some features will be removed or revamped.

Only concern I have about UCP is how they planned migration to that without any option to opt-out from beta-testing...