Idk about the root of Android/Google, but definitely a major product of theirs not functioning properly on another of their major products, so I agree that you'd think it'd be taken care of by now.
The funny thing to me is (which I've already shared in a similar thread about the sync issue), I didn't have any trouble at all when I first read about this issue. And that was when I read that the fix was supposed to be coming soon to the server side of things.
I just reset my phone because I decided to leave the Android N Preview. Here's hoping gmail will sync better now. I've had trouble since getting my 6P back from repairs, but had no issues before sending it out, or on the S3 that I used for backup while it was gone.