You are entirely right.
I've long said that optimising for "engagement", with no regard to what kind of "engagement" that is, is a paperclip maximiser.[0] Rewarding the posts that get the most comments regardless of whether they are positive or negative or thoughtful or shitposting, and the posts that get the most reactions regardless of whether the reactors (?) have or have not given it a few seconds of thought, is destructive to understanding each other and destructive to democracy.
See, I would rather Facebook not de-platform Trump, or any of his fans, or anyone else I don't like, but let's not pretend that Zuckerberg gives a shit about peace, love, and understanding. They have taken conscious decisions to prioritise "engagement" over anything else, because that is what makes them money. I get it, that's business, that is what they have to do. Likewise, we should do what we have to do to protect ourselves and to protect democracy: Zuckerberg and anyone that works at or has worked at Facebook should, to borrow a phrase, be unto us as heathens and publicans.
(You can extend this to Twitter too. I know, they scored some imaginary Internet points with left-leaning crowds by "fact-checking" Trump, but the truth is, with the algorithmic timeline providing exactly the same rewards to shitposting as Facebook does, they are as much to blame for this too.)
[0] https://wiki.lesswrong.com/wiki/Paperclip_maximizer