Add to that politics intervening threatening regulation unless they're allowed to tilt the scales. I can't even imagine how endlessly complicated that gets.
I've been debating this question internally for a while and also the question of algorithms. Subjectively speaking it seems to me that it's just as herculean of a task to come up with an algorithm that provides quality content to just about any user. I've tried some of these "alt-tech" sites/servies that claim to have no feed algos other than popularity and even the ones that have a few quality channels on them have their front pages flooded with all sorts of cooky, weird, bad material.
This is not a defense of Facebook (or Twitter), just some thoughts I had for a while now.
To be clear - I understand your point and sort of agree with it from a software engineering perspective; I just don't think that's necessarily the right perspective here. Every day we demand that governments and companies in all sorts of different industries do lots of hard, complicated, not-easily-computer-programmable, bug-riddled human processes requiring subjective judgement because they need to be done.
People & organisations aren't entitled to only do the things that need to be done which they can do with near-zero marginal cost with computer software - when they can do that, good for them. When they can't, tough.
Yes, I agree, from personal experience designing good Recommendation Systems is hard. That's a field I'm interested in too - out of curiosity what alt-tech sites have you tried? Would be interested in also trying them and exchanging notes.
I tried Locals, Gab (in their less controversial, earlier life while they still had an app store app), Parler, Bitchute, Rumble, Minds, MeWe.
I generally found that the experience is the exact opposite of Big Tech where you often get lost in the information presented to you and very often it’s low quality or annoying unless you go there to specifically watch or read or see something.