It's both. Social media provides a positive feedback loop for awfulness.

It certainly polarizes people. The people in the middle who aren't that passionate about things tend to just scroll past, but the “passionate” ones just yell at each other and either keep doing that ad inifinitum or they form an echo chamber where they can call others snowflakes.

It's not just polarization. Polarization is a natural state of human societies and is a good thing as it enables things to move forward (in either direction).

Silicon Valley corporations, whether for profit or by ideology, have pushed nazi/conspirationist propaganda to everyone in the form of recommendations for many years. To be fair, so have traditional media outlets, neither of which is excusable in my view.

Maybe someone will eventually take this into consideration in their design.

HN for example. I find this community conforms to my own notions of informative, open, and smoothly moderated.

Provided one stays within the local Overton Window, I agree.