User blog comment:ArchAngel217/Complaint About Those Complaining About UCP/@comment-25358237-20201208195918

Most of the people complaining seem to not see the issue with being on an old version of MediaWiki.

"If it's not broken, then don't fix it" - if there's a crack in your wall, do you get it checked, or do you wait until your house has fallen down?

They don't see the amount of work being put in behind the scenes to try keep things working and keep security up. The version was released in February 2012 and it reached it's end of life in May 2015. Even MediaWiki themselves urge sites to upgrade due to the security risks.

Other things such as glitches and missing content can be fixed and are being worked on. "It's harder to use" is a you problem.