I'm 100% aligned with you on this. The problem is that many people, especially younger millennials, don't follow these social rules. Aside from it being exhausting to listen to them preach their political beliefs at work, you can also be "outed" just by not agreeing with them vocally enough. I've had friends have to leave teams because of this dynamic.
It’s funny, my experience has been the exact opposite. Conservative boomer and older-gen-x employees where I work are very outspoken, loudly rehashing Fox News talking points in the cafeteria, seemingly projecting their voices as loudly as possible to try to get a rise from everyone else. I don’t know if they feel “safe” because they are nearer to retirement and have pensions (which have since been phased out and none of us younger folks have them) or what, but the younger workers keep their heads down and don’t tend to chat about politics.
I've definitely experienced the loud and completely socially-unaware older conservatives as well, but generally not at work. Is your career in danger if you disagree with these people? That danger is where it goes from an undesirable work environment to one that is genuinely bad for society.
If so, that seems like the same dynamic, just with a different hegemony. It's a horrible pattern for a workplace regardless of which view is the orthodoxy.