There's also too much "heels aren't supposed to be good wrestlers" in the mentality of modern fans, in my opinion. I got into an argument with a guy who kept trying to tell me that it's a good thing Jinder Mahal has no credibility because he's a heel, and they're supposed to cheat. There's too much reduction and rounding off of heel qualities, to the point of pantomime and you can't believe the villainy in the slightest, and villainy only works if you believe it.
Heels are awesome to people because they know wrestling isn't real. You used to be able to do those preordained "heel things" and get heat because people thought it legitimately made you a jerk. Now people know better and the performances of "heels" are less believable than they've ever been, because they are about that replication of performance as opposed to actually creating a nuanced personality that people can really believe is a dick.
Heels can cheat. They may not be above it. But top heels are still damn tough sons of bitches, and cheating in a big match emphasizes the ability of the babyface and gives them an out. Now heels inhabit this cartoonish realm of always cheating, to the point where wrestling almost undercuts itself by "not having instant replays" and not having second officials out there. And even the top heels in modern wrestling suddenly get glass jaws and are scared of their own shadow.
This is a tangent and I'm not sure how it even addresses the question, but too many "heels" are what someone mocking pro-wrestling in a 90's sitcom would reduce them to. These shallow tropes of cowardice and villainy instead of being legitimate athletes you hate because of their nuances and the actual effect they have on the babyfaces you admire.