politics

The combination of competence, the necessary skills, intelligence, and most importantly, the willingness to sacrifice oneself to effect change is...rare. It's also uncertain whether results would be positive.

Consider what is needed to pull off 'focused' violence - that is to say, assassination of key targets. You need to be sufficiently skilled to manage at least one successful strike. You cannot communicate with people to do this - it's far too easy to get caught in the modern day. You need supplies and equipment, and sure, guns are somewhat easy to get in the US, but they aren't the only thing you need. You need access and information, some of which is public, but some of which can be hard to get, and can draw attention by being sought (keep in mind algorithms are pattern matching to find this stuff).

Then consider the potential outcome of these actions. As mentioned before, organizing is impractical since it would mean getting caught before doing anything with much higher probability. Regardless of your skills, the chance of getting caught approaches 100%. You may be able to take out two or three key senators, or if you're very good and very lucky, a few supreme court justices, before being caught. At this point you will either be imprisoned, or you commit suicide to avoid this fate.

And what's the result? Violence of this sort to effect change is hard to pull off, but even harder to predict the outcome of. If you've succeeded in all plausible goals, you might manage to change the makeup of the supreme court - that's probably the best possible outcome you can hope for with this sort of violence, but right now on the gay front, the supreme court shockingly has yet to do anything too bad, so you may not want to provoke that shit. But there are a lot of possible bad outcomes. And as someone smart enough to pull this off, you're smart enough to see that. It could lead to increasingly strict rules, to retaliation against the group you're trying to help - it could even be the catalyst to strengthen your opponents position enough to make things worse elsewhere.

The idea of someone killing a bunch of the key bad guys is great, but it has so many impracticalities, and worst of all, such an uncertain and potentially worse outcome that it's probably just a bad idea overall, even as much as I too sometimes wish someone would just kill some of these motherfuckers already.