^^agreed.
if you go to a blues forum and ask who is better, stevie ray or mikael akerfeldt, im sure the answer will be stevie ray. however if you ask that question here the likely answer is akerfeldt
you cant say if 50cent is BETTER than opeth, you can say that opeth are better musicians, more more effort into their songs, have more diversity and 'progression', etc. but unfortunately alot of people dont give a shit if musicians work hard to make their music, or if its diverse. they just want something they can dance to or whatever. they dont care if every song sounds alike
i agree with what you are saying in a way uthark as i personally think that 50cent is shit and that opeth is a far better group of musicians, but music is very subjective