It's painful to feel back stabbed. I'm sorry you have been through this so many times.
I love learning about different things. I love sharing different ideas and perspectives. Medium lends itself to that. We can all agree to disagree or suggest other ideas in a respectful way. When people comment on articles with a "you are wrong... this is actually how it is" it gets my back up. I have blocked a few folk.
I don't think I have been bullied here. But I have experienced some not so nice comments. I have also experienced one writer showing up to see what they could get from me, when it seemed I might be worth knowing after the Medium Writers Challenge.
They tried to direct me to their work and spam me with a few comments to get me to sign up to their workshops to "improve my writing". There was no authentic engagement. Just seeking me as an audience. I don't think that's particularly cool.