I understand that you're on the side of the argument on the bias that "If it's in the game this way, then it's intentional" or "If it ain't broke, don't fix it". But what is the practical application of having a monster go unclaimed when someone disconnects? Or when one person out of eighteen dies to an instant death move? Or a ranger Weaponskills and the mob is kited out of range? Etc.
When a group of people is in full control of a mob, and it goes unclaimed, that's an error.
This game is you against the environment the game was developed under the premise of teamwork; with the players on one side of the line, and the monster hoardes etc, on the other. At no point was the game ever intended to be players stealing from one another. Players aren't an "unfortunate environmental circumstance"... Defending a glitch as an intended dynamic when it goes contrary to the general theme and presentation of a game is faulty thinking.
It's like playing poker and somehow getting 2 Ace of Spades in your hand from a fresh deck. You don't just 'keep going' and revel in your luck... You stop, fix the error, and move on.

