It's as simple as this:
HAs/HXs being the last man alive, followed by a dozen enemies and still winning the round is on one hand viable, because all he does is playing his class, but it's boring to watch, and somehow unfair because if he doesn't fail big time infantry can't harm him at all.
To solve this problem of who should be allowed/able to kill whom, just remove the necessarity to kill anyone at all - make master of the field appear ALWAYS at 2 ir 3 mins left. Problem solved. I don't know how many thousand times it has already been suggested, until this very day the developers still ignored it.