If I can see it and I view it as bad content it’s getting downvoted. Especially since such content usually is inflammatory political post from niche politic subs that have no problem espousing their politics in a “either you agree with us 100% or you’re wrong/the enemy”. The rest of the time it’s weird fetish porn.
I browse by all because it’s a good way to see communities/content I wouldn’t otherwise see if I stuck to a curated community list. Not being part of the community doesn’t matter because I’m still seeing the content and still behaving consistent with using the downvote button to collectively filter it out.
I think a better option is these communities opting for the post not to get sent to all. Which won’t happen because a lot of previously mentioned post; the target isn’t the community who already likely agree with them, it’s everyone else. Better yet these communities could implement rules against post that are clearly inflammatory/flaming but then where would they grandstand?