These are all private companies that have some space that they pay for from common carriers and open up to people
with constraints. They are more akin to shopping centers were the teenagers use to hang out in than public spaces.
It is not reasonable for random people to declare that some private company's comment section is a public square and thus can't or shouldn't be moderated.
If you want to grab a microphone and speak your mind, stand up your own server and do it. However, no private company owes you a thing.
Just because you want Twitter or YouTube or Reddit to be a public square doesn't make it so.
If you want to have the government compel private companies to do things, then say it. If you want the government to takeover private companies to provide the services you desire, then again, say it.
As it is, the companies that you are listing are working as private companies in a context of "they're not breaking any laws" and "it is not the government's place to be regulating what private citizens or private companies are saying or not saying."
I also believe that going down that path of "you must host all content that isn't illegal" to a private company is as equally authoritarian as "you must not publish any content about X".
As it is, the companies are making decisions about their ethics and bottom lines (from however their content is monetized) and working from there to decide what is and is not appropriate to host on their systems.