To answer your questions; imo...His is the second post in the thread. That is a location that most thread readers are likely to see and respond to. And that particular post insists on a problematic and sweeping generalization.
How can the responses have gone differently?
Indeed the initial responses were polite with reasonable objections and requests for clarification.
Things became uglier because of personal insults at the objecters and questioners.
We are/were discussing art, which is subjective.
Asking for clarification for a better understanding is perfectly fine, but it felt more like the OP was being asked to provide proof, show cause and effect, and to debate and defend their position.
When OP provided examples they felt illustrated their point, those examples were picked apart.
Perhaps the OP couldn't articulate the exact point they were trying to make, and once the discussion turned to debate, it went downhill.
That is what it looked like to me, and I grew uncomfortable following the discussion even though I also don't agree with the OP.
So I made my post about them being "hauled up on the debate stage".
Thank you for asking.