The problem is the level of discorse on social media.
Who is going to shift their opinion to the opposite point of view when the discussion consists only of those making shouty comments.
YOU ARE WRONG YOU (insert derogatory term) is not advancing the debate.
Such content fills up and drowns out those things, particularly when after those wanting to advance it by sensible criticism are then hounded across the internet by an army of lunatics.
All you need to do to silence an opponent is to create an environment so hostile that sensible opposition views are crushed out of existence.
That is what happens that would not happen if you were to hold a physical debate in a sports hall etc.
I've seen the drowning/flooding thing happen on all sides in pretty much all topics. It is seemingly a common tactic to coordinate a savage mass invasion of debates to destroy an opposing viewpoint.