User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-36153576-20201223091902/@comment-1038387-20201223110029

There are way more than "a few cracks" in Legacy.

The source code is largely unaffected. Only a couple of tags are discontinued, and closing tags have become more important, but the core code was updated to be up to date. "Removing wikitext from forums" is, in a sense, the most beneficial thing they did, but in a way you didn't see. Forums and walls were hacks of MediaWiki that required so many changes, they held back core software updates. Streamlining the bloated custom code is vital to keeping the code updateable. It won't be another eight years until the next software update.