These are private companies, though. They can police their content however they want and might determine that more restrictive rules are better for the product than loose ones. The host simply accepts the consequences of making the wrong choice.

They are not in the business of providing a platform for free speech. Just look at reddit for an example. The quality of their product has suffered because they allowed (and continue to allow) racist and misogynistic subreddits to proliferate. Thus, these segments of their user base also proliferate. At various points, they decided to take action. Whether those actions improved their product or not is debateable.

Social media platform users have no right to free speech on the site. They do have a right to start a competing website that allows free speech, though.