I agree that ads are a crucial difference and also you have agency along many dimensions such as how posts are portrayed to you from user interface look, to defaults for NSFW content, to autoplay or not autoplay.. all of that is agency to me that cuts off the potential for a toxic relationship at the root by making it so whatever part of the experience is unhealthy for an individual can probably be tweaked or minimized. Corporate social media just makes the UI however the hell they decide to make it and that is that until a huge amount of accessibility pressure forces some option to be added.

https://brutaldon.org/

Brutaldon is a great example of this accessibility through endless tweakability, you can view your Mastodon feed in a user interface that looks, feels and engages with you entirely differently, and there is no incentive for instances to block this kind of end user tweaking like there is for corporations.

I have never had an issue with pure chronological feeds, I think there is an intuitive fear that you won't see everything or that important things are drowned out the more you add to a chronological feed, but in my experience even in very large feeds paradoxically after a certain point every interesting account you add makes the feed more reactive and dynamic to what is happening in the outside world since it is unlikely you are bound to check your feed when someone just happens to post to your feed, and you are rather more likely to see people that are posting on your feed because it has something to do with something happening in that moment such as a sports game or a breaking piece of news... because if you don't follow too many high volume accounts most accounts won't be posting to your feed most of the time. Your feed goes from being a short collection you browse all the way through to shooting stars in the sky above, you only see the ones that happen to go by right as you are looking in the sky, but that doesn't mean that it is random that the shooting star is streaking across the sky in this moment... in terms of this metaphor.

Even still, to me the idea of an algorithmic feed isn't necessarily bad, it just feels like exactly the kind of overengineered, manipulative and needlessly quantitative "solution" I typically hate. Beyond that kneejerk reaction though I can see the use for viewing my chronological feed and then apply algorithmic temporary tweaks to the raw feed to stress different views. Maybe I get tired of seeing the same posts so I apply an algorithm to sort out repeats, and thin out posts from accounts dominating sections of the feed (maybe by artificially spacing them out elsewhere in your feed in a transparent way?).

Of course what the people building social media software usually mean when they say "algorithmic feed" is exactly what Bluesky is doing, it is the desire to locate power in centralized entities that can influence the feed even if it is ostensibly open or.. if everyone spontaneously decided to all leave.. could become decentralized...

edit I also like to imagine algorithms that could bring up much older posts from interesting accounts in a way that pleasantly skips around in time, or maybe an algorithm that takes every "boost" or "repost" in your feed and temporarily adds in the posts from the boosted or reposted account into your feed and marks them with a "would you like to follow?" button? Something between the 'subscribed' and 'all' feed might be interesting and useful.