Free speech does exist in the law, not just as an ethical ideal. The law states that the government can’t infringe on your speech.
Anyone who is not the government is free to block your ass if they don’t like you or what you’re saying.
Not all speech is worth defending. The only people who benefit from free speech absolutism are the ones with only horrible things to say.
I don’t think that anyone has an issue with the block feature. The problem is when the platforms themselves decide to arbitrate which viewpoints are allowed. This was clearly visible during Covid, when divergent viewpoints were penalized aggressively.
I am fine with blocking. However, it should be me who decides whose speech I don’t want to see, not someone else.