First of all, I'd recommend that you use or self host a Pleroma instance instead if you want to avoid the bubble.
>Why does *the mastodon bubble™* seem to be extremely allergic to anything doing any kind of automatic processing, like search or sorting posts by stars?
Anyhow, it all comes down to privacy, or an illusion of it. As fedi users tend to be on the fringes of the internet, they want an idea that they're more private here than on Twitter (where you can find posts to cancel people from 5 years ago easily). When Mastodon added in trending tags to the site, this caused a giant backlash from the idea guys orbiting Mastodon who claimed "this is literally harassing me". Reading this article in particular gives you a peek into the Mastodon bubble mindset as well; they love the idea of writing on their door a sign that says "MOM KEEP OUT" which she ignores anyway.
https://www.dailydot.com/debug/mastodon-fediverse-eugen-rochko/Of course this is in fact an illusion. Case in point; deletion requests. Messages are only deleted on the fedi if an instance tells another "hey delete this post", and many instances decide to deliberately reject these. Or infamously how DMs are not private due to the fact that each instances admins can read them (but they were never on forums either and same with Twitter). This has led to many instances restricting searches to logged in users since some people use websites with less broken searches such as Pleroma instances to do the searching, and needless to say this causes admins to sometimes ban people who are using their sites deliberately to dox people.
>And why does the critique of such projects regularly end in personal attacks against their creators?
It's the Tumblr and Twitter mindset, see what happened to Zamii070 as a great example of how that hivemind behaves. A few years ago they bullied a fanartist for drawing a character "wrong" to the point where she wound up in the hospital for a suicide attempt. Real or not, the attempt caused this behavior to be brought to the limelight, and then absolutely nothing changed afterwards. It also didn't start with Tumblr as this sort of behavior happened on places like SomethingAwful, Reddit, and more.
https://www.reddit.com/r/HobbyDrama/comments/hbxau7/tumblrsteven_universe_zamii070_aka_the_leftwing/ This tends to get results because many people, especially older or less internet savvy, will buckle under pressure.
Furthermore, in left wing internet circles once you're canceled you're forever ruined. No really. I mentioned this in a DM with someone, but those people never accept that you've changed. Once you're problematic you're always problematic, and if you try to get on their good side your past is just blackmail to them. So having the ability to wash away your sins or hide them and rebrand is nice.