I wouldn't say anyone can pick up a guitar and play. Trust me, I've tried to teach my wife.I've been playing guitar and bass for 15 years and drums for 8 years. I wouldn't consider myself any good. From a purely technical stand point I am a fairly clean player in most respects, but I could never write beautiful music like Opeth or Beethoven. I'm simply not creative or talented enough. That is why I never said that simply playing guitar makes it good music. I've seen and even been a member of plenty of bad bands. Now if you accomplish the skill it takes to play an instrument and make music people want to hear, THAT, my friend, is a challenge. Throw all that in a live situation and you're in for some fun.
The difference between a remix and a cover is that most cover bands don't claim the music to be their own and make money off the deal. They do it to play the music and get people in the doors to hear their crappy originals. I've been there.