As a GM and a player I can understand and empathize with Errant Knight's frustration because he's railing against something that drives me up the wall too. That insistence by certain parties on violating the meager handful of things in the setting that are more or less set in stone.

Look without certain constants we don't have a setting and if we don't have a setting then we may as well just all be sitting around talking about how our godmode mary sues are teh best always and foreveh and we then may as well all be in our own individual spaces so at that point why are we even playing together or rolling dice at all?

There is such a thing as contraints leading to increased creativity and that's a big element of good tabletop, so no there are no navigator/psyker combos and no you can't play a girl marine and no you cannot play a nice dark eldar. We need these limitations we need them to maintain a coherent experience with context.

... and no you can't play a girl marine and no you cannot play a nice dark eldar. We need these limitations we need them to maintain a coherent experience with context.

What about half-elder half human RT that was Commissar, Inquisitor, and renowned philanthropist (mostly with the opposite sex). Did I mention he is only 14.....ish?

Oh, you've met my newest player?

"The Emprah made a half-human half eldar Librarian, so it could happen again!"

"If an Archmagos does a lot for the Inquisition, he could become an Inquisitor!"

"If that Inquisitor needs to operate out on the fringe, they could give him a warrant!"

... nnrrg.