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.
We don't need conspiracies, people stink at this to begin with and most DO NOT CARE. The tech world is a bubble, we are less than 1% of 1%.
This happens, btw, when there are the most rules and heavy-handed moderation. Places that are less moderated, this rarely happens because people will directly call this behaviour out and the moderators are only intervening on important stuff, e.g., threats of violence, illegal material, etc.