This question asked about how to do item duplication in Minecraft, which on most servers would probably be considered cheating. But is a blanket ban on all exploits in multiplayer games appropriate?

Consider skiing in Tribes for example. It was pretty clearly an exploit not intended by the developers, but it became so popular that the sequel was designed around it.

Contrast it with whatever you call this glitch in TF2, in which a player can hit people with a flamethrower from across the map.

Where is the dividing line between an acceptable exploit and an unacceptable exploit?

This question asked about how to do item duplication in Minecraft, which on most servers would probably be considered cheating. But is a blanket ban on all exploits in multiplayer games appropriate?

Consider skiing in Tribes for example. It was pretty clearly an exploit not intended by the developers, but it became so popular that the sequel was designed around it.

Contrast it with whatever you call this glitch in TF2, in which a player can hit people with a flamethrower from across the map.

Where is the dividing line between an acceptable exploit and an unacceptable exploit?

Edit: I'm aware of this question, but I think this is a different issue. That question is asking about what cheats are ok to discuss. The examples given are unquestionably cheating, but may be OK depending on whether the game is competitive multiplayer or not. My question is about how you judge whether or not an exploit is a cheat or just a fun quirk of the game.