"Realistically", a Chainsaw is totally worthless as a weapon. No, seriously. Not too long ago sometime tried to fend off a wild cat with a chainsaw.
The Mountain Lion got away with a fairly shallow wound.
Chainsaws are meant to chewing up hard, dry wood. Not soft, gooshy flesh. In addition to not doing much damage, the chain would quickly get stopped up with gore. They would, also, recoil pretty hard - people have injured themselves when they didn't bring the saw into the tree correctly and it glanced off.
tl;dr, the chainsaw is inherently unrealistic. Ergo, attempt to apply realism to it kinda fail.
That and well, the last thing the 'Saw needs right now is a nerf.
Eh, if chainsaw is so lackluster, why protective clothing is so thick and robust?
The reason why basic chainsaw is not optimal weapon is because cutting chain structurally optimized to cut rigid wood, you are correct in that respect. BUT its NOT a butter knife. Chainsaw accidents tend to be extremely gruesome for a reason. Damage potential is staggering.
Getting chain jammed by gore is not very likely, chain oil is very thick, its almost like porridge when you apply it to the chain. As a matter of fact, I think gore might function as lube.
"Kickback" of the chainsaw is directly relative to the rigidness of the matter you are trying to cut. Crappy old Husqvarna in my family's summer cottage kicked like crazy when I tried to cut dry pine log, but when my uncle cut down smallish spruce after rain, it was very tame. I doubt that there will be any kickback in case of Bloats fat belly.
Biggest reason why I wouldn't use chainsaw as a weapon in zombie apocalypse is its weight. 13 kilos is too much for me personally, but I'm pretty small dude.
I bet stronger guy with chainsaw (preferably with some kind of raincoat/gasmask) would spell hell for any zed that wanders too close.
tl; dr, Chainsaw is not optimal melee weapon, but its image and kick-*** appearance make it perfect for a game like this.
@Krieg Jaeger: Why there isn't any proper 40k FPS with chainswords and poopoo? That universe screams for a game like that.