Why isn't the FBI raiding all Silicon Valley companies like Facebook, Twitter, Instagram, WhatsApp, TikTok, Reddit, Google, Yahoo, YouTube, Disqus, Wikipedia for censoring the World through their Ban cartel violating the constitution freespeech laws?

Should newspapers be forced to print every letter ...

What arguments like this fail to recognize is 1A means you have the right to keep your damfool mouth shut. 1A means you cannot be forced to say anything, a right backed up by 5A. 1A and 5A as they apply to speech prevent government from forcing you to say something AND stop government from not letting you speak.

Lemme make this simple - Freedom of the press belongs to the person who owns the press. You don’t like what a particular press (the social media you reference above is the press in this case) does, start your own and you make the rules.

To a flat Earther, what's wrong with the idea that gravity is simply a force inherent to space which operates only in one dimension? Why do they go further and try to deny gravity rather than just saying it's different than physicists claim?

Restrictions of course apply. See Supreme Court rulings on what can be restricted, i.e. child porn, inciting to violence and a couple of others.

They have not violated the U.S. Constitution and freedom of speech laws. Dunno about other countries.

Government owned companies are also covered by this, but these companies must allow speech the company may not agree with.

What was your best sex experience that still makes you horny?

Companies that are privately owned, owned by stockholders, etc. are also covered by this. These companies cannot be forced to provide space or a platform for speech they do not agree with. This is freedom of speech. I realize you may disagree.