In reality it's like Comcast. You could theoretically switch ISPs, but realistically and in practice it's a monopoly.
Sure some businesses are forced on to the platform to communicate with a subset of customers but it's extremely rare that they aren't on all the social platforms AND have their own website.
Family members that are on Facebook have phone numbers and are on other platforms. Maybe you can't spam them with links to every conspiracy website you come across or an endless stream of your kid without them becoming annoyed, but you absolutely can communicate with them. Facebook has only stayed relevant because of the natural lag in popular websites (older folks always get on late) and by buying platforms people have switched to in recent years likes WhatsApp and Instagram. But people do switch and people also are on multiple platforms
I haven't used Facebook for many years and I can contact family and friends just fine. Granted I use WhatsApp, which is owned by Facebook, but WhatsApp doesn't suffer from censorship (to my knowledge).
I don't know what Facebook is for, but I'm told that Telegram is a great replacement for Whatsapp and even people who both have Whatsapp seem to prefer Telegram between them.
These 3 are very similar in their values, operate under the same legislation. The latter is especially worrying for people not from the US, because foreigners' rights are completely unprotected.