Furthermore traditionally we have drawn line beyond which speech is not free (for example shouting fire in a crowded theatre is traditionally not allowed).
... I'm going to assume you left out a "not" in that sentence ...
That's exactly my point!
(As an aside I tend to read downvoted comments first because I want to see why they were downvoted. It's more of a highlight than a downvote for me.)
I will defend people's right to say things I don't like hearing. However I will also defend other people's right to not listen (as long as they don't try to prevent the speech from happening) - that is also a freedom.
To modify a quote: Your liberty to speak ends where I am forced to listen to what you are saying, my freedom to not listen ends where I prevent you from speaking.
Downvoting does not prevent the speech from happening. It merely says I don't like this. Flagging does...
But that is exactly what is happening. Liberals, or libtards would be the more correct term, are drowning everything they think they disagree with, creating echo chambers. This is what divided our societies and brought us Trump, Farage, LePen, etc.