No, lying is bad. Sales are sales, nothing else. If companies also want to release subscription/stream numbers or total player numbers (the latter many already do) then that's what they should do. But they shouldn't pretend something is a sale when it isn't.
Oh, and is the gaming industry really more niche than the music industry? I mean in terms of $ value alone I'd be very surprised indeed if the gaming industry wasn't a fair bit larger than the music industry.
I mean niche in audience and reach. Estimates have it that there are 2 billion gamers and I'm sure that almost every human listens to music.