Not defending the practice per se, I have agreed (with you and others) that it brings imbalance and tends to be boring more often than it brings real high-level clashes (besides the community feeling, these organised large-scale battles are something unique that I have always enjoyed in Warcraft and can not be found anywhere else in the game).
It is more like I want to point out the objective truth that group-syncing has always been a thing in WoW, and has never been a reason to get banned. Why am I doing that? long story, has to do with some people denying that objective truth, telling others to mass-report and/or harass community leaders (yeah, I have seen that happen with my own eyes - people are abusing their status/followers for evil, that includes certain community leaders themselves, but also “streamers” and such). Partly I am doing this because of forum-fun of course =D
Almost no one can carry an epic BG with 3 players, some classes in certain BGs (Ashran foremost) can do that. Otherwise, you are super-dependent on other people’s performance, even if you want to take the lead and shout commands (which I have done a lot in past years - I even wrote an addon for commands). So… Na… sorry, but telling me you get 80% win-rate because 3 players premade is lunatic 
Maybe it’s because you play horde xD They have been used to zug-zug victory in most epic BGs. Anyway, I play small BGs most of the time. Epic BGs is no fun being at mercy of so many random players.
I could not care less. If you knew how people look down upon me just for playing Prot Pala in PvP. I know exactly those people ignore all other problems regarding balance in PvP when it does not affect them + some of them participate in other shady practices which “should” not be done either. I could point at some people in this thread…
But anyway: I agree that we all could have a better experience when stuff get’s regulated and balanced better, which includes shutting down group-syncing. People have their right to demand change, but don’t deny the objective truth mentioned above. The best solution would be full cross-faction queues for random BGs. I fear Blizzard will not do that though - Cross-faction groups can now (11.0.7) queue for unrated PvP!