Was the QR/Disc thing a real problem for most people.
IIRC, it was never a problem for good quality QRs that were properly fastened. The first problem was that many beginners didn’t know how to fasten a QR, so they would wingnut it up. Also, a lot of cheap skewers had exposed cams that would get full of dirt and rubbish and corrode, so they wouldn’t clamp properly.
The steel Shimano skewers were the benchmark, I don’t think anyone ever had a problem with them. Another problem was that people would buy silly lightweight titanium skewers to save a few grams or to pimp out their bikes with expensive anodized stuff. Those skewers often didn’t clamp as firmly as the cheap Shimano ones.
Apparently, people also ground down the lips on the dropouts to make it easier to change wheels in a hurry (I’ve never seen this, but there were rumours about it). I can understand someone racing at the world cup level wanting to save five seconds on fixing a flat tyre, but anyone who did this because unscrewing a skewer a few turns to clear the dropout was too much trouble really deserved to lose their teeth.
Those things didn’t matter so much with rim brakes because the braking force wasn’t trying to rip the wheel out of the dropout, but it was potentially problematic with disk brakes. Hence the general switch to through axles.