Faction-based MMOs are mostly a thing of the past. The only ones left with much of a player base are World of Warcraft and City of Heroes, which are both over fifteen years old. Attempts to make new ones have crashed and burned, since splitting your player base is not good for the health of a game. Even in CoH, which does divide heroes and villains into separate zones for most of the game, you can switch sides or go middle ground easily, so you can group with everyone. ...And that's still enough of a limitation that few people play on the much better-designed villain side.

In modern MMOs, the most divided the players get is at the start. Most games these days start everyone out in a newbie zone which is likely to depend on your character's race or class, so they can have some setting-specific story tailored to what you want to play, as well as not overloading a new player with options. After that, they tend to make it easy to get to whatever the main hub of the game is. It's been clear for a long time now that the less restrictions a game has on letting the players do what they find fun, the more successful it's likely to be.