Did you use to mix with headphones?
I don't know anyone who uses headphones to mix. You should always mix on monitors and in a tuned room if possible. Referencing a mix on headphones is another matter entirely, though.
I didn't have any room treatment back then, so yeah I used to mix and reference a lot with headphones (and loud volumes, because young and stupid).
Checking wideness of the mix with headphones is quite important in EDM as well, but I've started using lots of reference tracks to eliminate headphone use as much as possible.