I’m from a PvE-RP server, so I don’t run into this issue, but seeing the back and forth conversations between people on PvP servers has me thinking.
PvP in classic is heavily dependent on gear. Not having gear means you don’t stand a chance against people that do have gear. It’s not even a question, especially when geared people can pump out significantly high damage very quickly. Just cause you’re a level 60 doesn’t make you suddenly strong. Lol
The only way to currently -get- gear, is to do dungeons. Which these people who are on unbalanced servers, cannot reliably do. There are no world quest rewards that do anything higher than greens for the most part, and they aren’t usually very good green items. All the end game stuff requires dungeon completions to get better gear.
Even if they forgo going to these end game dungeons, and find some other way to grind their way to level 60, they still are not going to be able to compete properly. Due to a lack of gear, and probably also due to a lack of training (Not being able to really farm resources, and being on the smaller faction, means gold is going to be harder to come by).
So, even if people -were- to follow the advice of these people saying to just “Go somewhere else” to avoid the zerg pvp’s blocking off dungeons. it in the long run, won’t help. People will still be cut off end game, and PvPing does not get you gear. So time you spend trying to fight, at a massive disadvantage is time completely wasted, and not helping you at all.
So now what? the Imbalance is still to the point, even if people do rough it out to 60, using less reliable methods, they cannot compete with the lack of gear. 
And if everyone from one faction decides to just up and leave, for example to a PvE server, you’re servers are not going to be able to do the AQ events, and your server effectively becomes a PvE server, with no one to fight with.
What’s the end goal then? The people that refuse to address this imbalanced factions problem, and just use tired catch phrases to attempt to ignore the issue. Are you trying to turn your own server into a PvE server? 
One that can’t even unlock some content, because it requires both sides to contribute?