Surely you can provide a better experience on your server by moderating the users who regularly post spam and other offending content on the live feeds a little better instead of having to resort to disabling the live feeds...

We certainly do, but the live feeds on mastodon.social are things posted in the last few seconds, it is essentially a pre-moderation view.

It is neither the best way for newcomers to find their community, nor much use to many established users. If people want to drink straight from the firehose, they can, but we do not recommend it.

to be fair one can say the same about the Trending feed, in the sense that it features a pretty homogeneous side of Mastodon that focuses on the same subjects over and over (e.g. exclusive focus on U.S. issues, technology, cats when people have other pets or none at all, etc.) and this can discourage people with more varied interests or lived experiences beyond that. We should be encouraging more diversity of interests beyond those things. The Trending feed does not sufficiently do that, despite the lack of an algorithm.

(this is kind of tangential to my earlier point about moderation, but I still feel it is worth mentioning)