Platforms like Facebook, YouTube, and Twitter are basically monopolies. They are the only services in their class to take seriously if you're looking to gain a following. If they didn't exist, alternative services would spring up. But alternative services know they can't compete with FB/YouTube/Twitter, so none exist. When people say "if you don't like FB's rules, use another service" it ignores that Facebook is the reason there isn't another service and thus has some responsibility to uphold values we've collectively decided as a society are important.
The issue is not whether Facebook is breaking the law but whether philosophically the market leader in a category should get to decide who can use their product when their product category is fundamental to modern life. Saying "no one is owed a platform" brings us no closer to an answer.