No MMORPG I know of ever asked players to define what an exploit is, and at any rate whether you call it an unintended mechanism or an exploit really doesn't matter because you have no rights in a MMORPG, so if SE wants to do something about this it doesn't matter what players think to begin with. An enrage of any kind is meant to kill your party in a very short time (like under 10 seconds). If they do not it just means whoever designed it was dumb. But since no dev is going to say, "We're too dumb to figure out how to make a boss automatically kill everyone' you instead get this standard spin of 'players are creative!' to save face.

But if history is any indication, it'd take at least 3 months before this gets fixed even if you start bumping it every day, especially given this is a fairly trivial issue compared to the other things SE ought to be working on.