But you can't learn what you can't hear. If a pair of headphones have a very poor response over 6KHz or below 100Hz, for example, they're going to have limited applications.
If you sweep with a band-pass filter through those frequency ranges you'll actually find little you can't hear, IOW little you can't learn...

The response over 6KHz is fine, I concede it may be better/different on others but that's different to saying there ain't enough full-range consistency to work with. I've got so used to them, and how they are going to translate now I'd probably find it difficult using anything else. Likewise if I was coming from a pair of M50's or anything else I may not like them because I'd got used to those.
Below 60Hz is the only area I have to employ some methodology to measure the actual energy down there rather than trust my ears. For example if a sub 50hz rumble is coming from a Piccolo patch it ain't likely to be anything that I'd want. So in actual fact you can even learn procedurally to counter what you can't hear. So the idea of a/ not being able to learn what you can't hear AND b/ these particular 'phones aren't adequate enough to learn are both spurious claims...

I can however understand when
IF one has a choice they may not be the best choice out of a set of alternatives but I'd merely venture they are one of the better all-rounders in the given price range.
Granted they are not ideal but what pair of cans is? Certainly nothing sub 100 quid.
Being as the original question here was actually:
Best studio headphones for under £100? Not to have included the HD280's would have been a glaring omission IMO.