As far as I can tell the debate rests on the fact that scav-players have things to gain without risk. I actually like the idea of the mode, but I can see the point that the game feels so tense precisely because you stand to lose something.
The 'unfairness' feeling kicks in when you think about it from a non-scav player perspective, e.g.: "wow that guy spawned in with an AK but stood to lose nothing / gain everything whereas I came in with my AK with the chance of losing it"
This is the reason the devs put a cooldown on it.
However I don't think that adequately adjust for the fairness in one side standing only to gain whereas the other side is actually risking something. Therefore some benefit, IMO, should be given to players who skill player scavs. I think a human who kills a human scav should get something special out of it, even if it's something small: experience boost, health pack, just something for having gone against a guy who stood only to gain from your death without himself risking anything.