This is all due to googles attempt to make a better email system rather than complying with standards. It smacks of how MS tries to tweak open standards to their liking to make a proprietary system. It usually just irritates people.
I'm sure there are some people out there that use google's labels for their email, but I don't know many.
Most people now have multiple email accounts. They should operate in similar ways to avoid confusion. That means conforming to open standards.
Everyone has a gmail account because it is free, offers plenty of storage, and is available everywhere. It has nothing to do with labels or conversation threading. We would all be better off if google reverted to a compliant IMAP protocol.
just my 2c,
kman