I am sure that there are some people who exhibit the behaviors you're describing, but I really don't think the group as a whole is disinterested in prior work or discussion of philosophy in general:
https://www.lesswrong.com/w/consciousness (the page on consciousness first citing the MIT and Stanford encyclopedias, then providing a timeline from Democritus, through Descartes, Hobbes,... all the way to Nagel, Chalmers, Tegmark).
Now, one may disagree with the particular choices or philosophical positions taken, but it's pretty hard to say these people are ignorant or not trying to be informed about what prior thinkers have done, especially compared to any particular reference culture, except maybe academics.
As for the thing about Aella, I feel she's not as much of a thought leader as you've surmised, and I think doesn't claim to be. My personal view is that she does some interesting semi-rigorous surveying that is unlikely to be done elsewhere. She's not a scientist/statistician or a total revolutionary but her stuff is not devoid of informational value either. Some of her claims are hedged adequately, some of them are hedged a bit inadequately. You might have encountered some particularly (irrationally?) ardent fans.
The epistemology skews analytic and also "philosophy of science". It's not inherently an issue, but it does mean that there's a reason that I spend a lot of time here on orange site talking about Kantian concepts of epistemology in response to philosophical skepticism about AI.
A good example of the failing of "rationality" is Zionism. There are plenty of rationalists who are Zionists, including Scott Aaronson (who I incidentally think is not a very serious thinker). I think I can give a very simple rational argument for why making a colonial ethnostate is immoral and dangerous, and they have their own rational reasons for supporting it. Often, the arguments, including Scott's, are purely self interest. Not "rational."
>My personal view is that she does some interesting semi-rigorous surveying
Posting surveys on Twitter, as a sex worker account, is so unrigorous that to take it seriously is very concerning. On top of that, she lives in a bubble of autistic rationality people and tries to make general statements about humanity. And on top of that, half her outrageous statements are obvious attempts at bargaining with CSAM she experienced that she insists didn't traumatize her. Anyone who takes her seriously in any regard is a fool.
https://www.lesswrong.com/w/epistemology
https://www.lesswrong.com/w/priors
https://www.lesswrong.com/posts/2x67s6u8oAitNKF73/ (a post noting that the foundational problems in mech interp are grounded in philosophical questions about representation ~150 years old)
https://www.lesswrong.com/w/consciousness (the page on consciousness first citing the MIT and Stanford encyclopedias, then providing a timeline from Democritus, through Descartes, Hobbes,... all the way to Nagel, Chalmers, Tegmark).
There is also sort of a meme of interest in Thomas Kuhn: https://www.lesswrong.com/posts/HcjL8ydHxPezj6wrt/book-revie...
See also these attempts to refer and collate prior literature: https://www.lesswrong.com/posts/qc7P2NwfxQMC3hdgm/rationalis...
https://www.lesswrong.com/posts/xg3hXCYQPJkwHyik2/the-best-t...
https://www.lesswrong.com/posts/SXJGSPeQWbACveJhs/the-best-t...
https://www.lesswrong.com/posts/HLJMyd4ncE3kvjwhe/the-best-r...
https://www.lesswrong.com/posts/bMmD5qNFKRqKBJnKw/rigorous-p...
Now, one may disagree with the particular choices or philosophical positions taken, but it's pretty hard to say these people are ignorant or not trying to be informed about what prior thinkers have done, especially compared to any particular reference culture, except maybe academics.
As for the thing about Aella, I feel she's not as much of a thought leader as you've surmised, and I think doesn't claim to be. My personal view is that she does some interesting semi-rigorous surveying that is unlikely to be done elsewhere. She's not a scientist/statistician or a total revolutionary but her stuff is not devoid of informational value either. Some of her claims are hedged adequately, some of them are hedged a bit inadequately. You might have encountered some particularly (irrationally?) ardent fans.