I always laughed at the name "Genius Bar." The average MacRumors member is more knowledgable.
That's a silly statement.
The issue is not "who is smarter" in some sense (and don't be so sure of the smarts of Joe Random Internet Commenter...) but who has better support machinery.
The Genius Bar guys have a lot more software and hardware at their disposal for diagnosing problems, they have a lot more tech resources (ie confidential written material) provided by Apple, and don't diminish the importance of seeing a constant stream of problems and thus seeing the patterns in how devices or software fail.
It's also silly to extrapolate from a bad experience in your random home town to the entire world. I'd say I'm substantially more knowledgeable than the "average" MacRumors member, and I have no complaints about the ten or so times I've dealt with Genius Bar folks over the past fifteen years or so. They've always been polite, on at least two occasions they replaced broken hardware (out of warranty, that I expected to pay for) immediately and with no complaints about "user error", and on at least two occasions they fixed SW problems I could not resolve.
Sure, there have also been the hardware that's broken and can't be fixed --- and that's part of life. Sometime hardware dies, and it's simply dead --- fixing is impossible to so expensive it makes no sense.
The impression I get from most of the "I hate the Genius Bar" stories I read (maybe I'm being unfair, but this is the vibe I get from the way the author tells the story, then language style and tone, etc) is that someone tried to lie to the Genius Bar, got caught, and is now pissed off.
You know the sort of thing:
"My phone just stopped working for no reason"
"OK, let's run a diagnostic. Hmm, the liquid detector says it was fully immersed in water yesterday. Does that sound right?"
"What the hell???? Are you accusing me of LYING about my phone falling in the toilet??? I've never been so insulted in my life. All of Twitter shall hear about this outrage."