Even a split party is playable, and if the Dungeon Master wants them to reconnect, he can make it worthwhile with the right incentives *smile*.
I wonder if Dungeon Masters cater for that in the start? Its kind of a cheat if you think about it because it allows each party to know what's going on with the other even though the characters aren't supposed to.
Metagaming can always be an issue, but if the Dungeon Master needs them to be uninformed, then he would have to play them separate. Makes for longer games, but it cn be necessary.
That could work in a tabletop environment if you have the space but it could make the game lag while waiting on the other group to get their turns in. In a Play By Post environment not sure how that would work without revealing what's happening to the others.
Play By Post systems, depending on the software, can isolate a chat thread so no one else sees it except listed users. This would keep the separate groups ignorant of the actions of the others.
But Gk, a split party, creates more work for the Gamemaster. It is acceptable, to have characters who are natural loners, or a character that is naturally mischievous, within the party. It even adds flavor to the mix.
It could prove difficult for the party leader, to keep the party on track, if most have a tendency to go their own ways.