Oh, forgot to mention it was a five minute per turn live game.

Yes, it is common etiquette. When games take so long, 2-4 hours often, playing a non-game where one or more players didn't show up is annoying and unfufilling. Let their NMRs and CDs hurt their RR and then draw/cancel. In the future, join games with RR requirements or higher points.

Note that it's considered to be good etiquette by a portion of the population
1) not everyone agrees
2) it's not enforceable per se (although two players being banned in the same game you can ask the mods to cancel, two players going CD just naturally by being AFK is not)

Generally speaking, I am in the "PUNISH THEM" school when it comes to first turn NMRs in live gunboat games. I like to play until the irresponsible bastards have CD'd and then Draw the game so their RR is hammered, as it should be.

Jeff: Cancelling a game doesn't remove the penalty from their RR. There's no need to draw instead of cancel for RR reasons.

I've asked the question of more experienced players in games who refused to either vote draw or cancel...generally the answer comes back that they used to vote draw but not any more. They got tired of watching other stubborn people stay in unbalanced games picking up the easy points. So over time they decided to do the same.

What would be the difference between drawing and canceling?

I believe I am right in saying that if you draw a game, those remaining players (you must wait until a player has shown as "left" rather than just "Missed the last phase") will share the Dip points, whereas if you cancel, it is as if the game has never existed.

Personally, I will always vote "Draw" in these situations as opposed to "Cancel" because I believe that those who have bothered to stick with the game deserve to share out the Dip points of those who CD'd.

Draw splits the pot among the remaining players.
Cancel returns the points to everyone and removes the game from completed games.