Those sounds like largely unrelated concepts that just happen to overlap somewhat in practice, and are also very individual. As a private person I don't lose anything at all by not using social media, but if I owned a local pizza shop I'd be losing a ton of business by shunning hat avenue of advertisement.

Personally I think the most useful definition for censorship in the context discussed here is *government* censorship. A company offering a product isn't forcing you to engage with it, even if it is a benefit to do so. You cannot in any way evade the oversight of your government without risking criminal penalties. Amazon can deny you their services. The government can deny you your life and freedom.

It's why the 1st Amendment protects us again government control of speech and assembly, but not the censure and pressure of our peers.

The first amendment protects you from (mostly only direct) government retaliation on your speech. It does not define what is and isn't censorship. It doesn't even protect you from the government circumventing it by having most communications go through private avenues and then strong-arming those private entities to regulate speech. And it certainly doesn't protect you from private censorship from massive corporate entities that seemingly want to have a corporate autocracy.