I think a big problem in academia, and a significant reason why it has gone downhill so much ideas wise, is structural.
Or rather, there are two significant structural problems.
One is "success by citation". That is an academic's success is to significant extent measured by their citation index (or similar measures), i.e. by how many people refer to their work. The citation index however doesn't differentiate based on the content of the citation, so even if lots of people are citing someone's work only to say it's rubbish, that person still gets a high citation index.
The second issue is that the best and fastest way to make name for oneself in academia (or sciences) is by coming up with a novel, paradigm-shifting idea, or by disproving an old paradigm. This "success through novelty" means that academics are highly incentivised to come up with something, anything new, that goes against established learning, even if it appears nutty. And other academics are incentivised to hitch their wagons to such a novel idea, as they then stand a chance of being part of the early adopter crowd reaping the secondary rewards of being part of the trailblazing crowd.
Note though, that such a novel idea can not be something that can be easily debunked. This is easier in fields which are more analysis than measurement, but it's not impossible in hard sciences either. One just has to be more clever about it.
In short: a significant method to achieve academic success is to say something a lot of people will talk about, which goes against previous wisdom, and can't be easily debunked. This means the aspiring academic either has to massage the studies, or just abandon any pretence that they're attempting to find things out about an external reality.
When one puts together success by citation and success through novelty, and removes any ties the system may have had to common sense and observable reality, the results are a system which rewards and feeds novel, outlandish ideas, such as queer theory.
And once a particular academic's career has been made through a particular novel theory, no matter how batshit divorced from reality it is, you can be sure that academic will keep pushing that idea as long as they want to keep their career going. Thus giving surprising longevity to these outlandish ideas, which initially were little more than an attempt to find an attention-grabbing niche.