Plus, unfortunately, nothing has replaced it - or offered anything that comes close to Twit in terms of functionality and ‘connectedness’
For two very specific sub-communities that I belong to, I heartily disagree with this.
Both Mastodon and Bluesky match the platform exactly, and also go above and beyond it, for features - if you don't count a CSAM-generating predictive text friendbot as a core feature.
For web development - which moved almost entirely to Mastodon early in Elon's reign, with every key influencer giving that movement traction - there is now very little on X and the exact same 'vibe' and community space there was now on Mastodon, but just on a different platform.
This is also my experience of the very specific 'people who post about cycling in Edinburgh'. Barring the council / edintravel and a handful of politicians, there is only a small handful continuing to post to X over and above Bluesky. For edi.bike and others, there is higher engagement with posts on Bluesky now than there ever was via Twitter/X.
Follower numbers are a big part of this - companies, orgs and political bodies mistakenly see X/Twitter as bigger when in fact for actual engaged users still on the platform - not just with an inactive account after they stop using it over common decency issues and problems with its governance - those users have gone elsewhere or given up on microblog-style social media altogether.