The sort of ridiculous theories that SJWs spouse (and often misinterpret) have existed in academia for decades, and while they have ways been the laughing stock of more scientifically minded academics, it largely stopped at that. The problem arose with the popularization and bastardization of these unscientific theories, combined with the puritanical zeal of its new adherents and the the advent of social media. Now we see people publicly "exposed and shamed " as racists and sexists for entirely innocent actions such as the table they were sitting during a symposium, or their haircut of choice. Some professions are particularly affected, like college professors, who how have to exert self-censorship to great lengths to avoid causing a commotion (and possibly losing their job)If the concern with people obsessing over a cause is that they see the world and all its problems through a single lens, and so come up with non-mainstream political of philosophical frameworks (e.g. queer theory), then surely to the extent that those theories are not actively dangerous, it's a good thing from a purely Millian/liberal standpoint that they exist, and so a good thing that people are able to come up with that perspective. Okay, you wouldn't want everyone in the world to adopt that perspective and lose sight of other important problems and ways of interpreting the world, but it's always useful to have around an articulation of other perspectives, deriving from the struggles of particular groups. Surely that benefit outweighs the eye-rolling that might momentarily be induced if you opt to engage with someone with whom you disagree.
Again, I'm not saying this is going to bring about the fall of western civilization, but it's a real problem and for some entirely innocent people there have been very real and bad consequences.