I’ve walked away from Facebook, but I’m still negatively impacted by their algorithm which promotes anger, division, and conspiracy theories.

This actually highlights the point well I think. The cost of walking away from Facebook is too high for most people even though they know its' bad for them.

Take myself for example. I only ever get angry when I browse my facebook feed and for some reason I've actually taken steps to ensure I get angry when I browse my own feed (chalk it up to silicon magic). I would like to leave facebook, but if I do I'd lose messenger which is the easiest and most consistent way for me to keep in contact with dozens of people (who mostly don't make me angry).

If facebook protocols were open source, then by now I would likely have dozens of different options to take my friend's list to a messenger only app that does not include a feed for me to angrily browse.

Lowering the cost to leave is a benefit to everyone since it reduces the reach of that anger inducing feed.

And how old are you? I don't think it's too much to expect for you to be able to manage your own emotions by now. FB has nothing to do with that.

Isn't the Messenger app a "messenger only app that does not include a feed for me to angrily browse."? They also seem to have standalone web and desktop versions at messenger.com

We still need there to be suitable alternatives, so there needs to be some regulation at least, to encourage competition and/or to prevent companies from reaching a point where there are no longer alternatives.