For those stating it's a "First come first serve" , it really isn't. Why? If it was a first come first serve than other parties wouldn't receive rewards for contribution of damage. Only the main party who engaged. This would be "First come first serve". It's also like stating "FATE's" are first come first serve when it's a event for everybody.

An prime example of first come first serve is like mining iron nodes in New World or Runescape, etc.

TBH, it's like a grey area.