So Quinn has a casual culture and hires anti-suit people but there is no culture and they don't hire Associates they think would fit.
No, I think the point is that the culture is imposed, not simply that exists because people are bred to it. I've known plenty of people who've moved from Quinn to more formal shops, or vice-versa. Generally, they change their dress habits, etc. to fit the guidelines established by the firm they're with. As I said, big firms choose people much less on "fit" than on perceived ability (for which academic success is generally accepted as a good proxy).
Since I never worked there, this may be an unfair generalization, but my perception over the years has been that Quinn would hire anyone who seems to have the intellectual chops and is willing to put in the hours. And for whatever limited value this anecdotal information is worth, I know people at Quinn who do wear a suit every day even though they obviously aren't required by the firm to do so.
Honestly, you won't be "right" because you're extrapolating from some non-representative information. I'm sorry if you take that personally, because that's not my intent. But this is one of the few subjects that comes up here where I can actually contribute some useful first-hand knowledge, so I felt it was appropriate to point out that what you were putting out there was flat wrong.
Enjoy your lunch.