>>724666932
Well, yeah many of them are counterproductive , insular, or holding to a particular "way" with such rigidity out of fear of what happened with the Fall. Deldar basically decide to keep on being degenerates to the max in order to ensure that Slaanesh eats someone else first, Craftworlders stay very disciplined and ensure that you follow the various Ways, even the Corsairs as you mention go around devoting themselves to that shit until they realize its not going to be the terminal point (kinda like a student fucking around hostels in europe after college, busking, and fucking in flophouses until they realize that's a nice experience but isn't really going to set you up for a comfortable life in your 40+ years). However the Pirates/Corsairs, still have people who think maybe that's a solution to their issues and takes awhile before they pick another path.
>>724666947
That's the simple default of the Imperium's dogma more than anything else, not even so much of the Emp himself (who obviously made use of not just DAOT but also Aeldari Webway related hardware) and even the Primarchs (the whole thing about Girlyman, his Aeldari friendly cult leader girlfriend, and all the benefits that come from that) and of course how varied Rogue Traders, Inquisitors, and others occasionally work with "forbidden by doctrine" alternates. Spess Mahreens and the like often will recognize that between Aeldari groups and Chaos Marines/cultists, Tyranids, Necrons or other groups that its the lesser of two evils and often work together - even the space elves often attack humans because the idea that they're doing stupid shit and are going to get the whole planet killed Hell, even the whole thing about Tau Gue'vesa having a better life than by some Imperium controlled worlds suggests that much like everything else in grimderp, the dogmatic shit and the huge bureaucracy that is operating to keep itself going isn't exactly the actual truth of the universe.