Just because there might be a better guitarist,drummer,etc.. that does not make someone elses music less perfect or good. You could be the biggest wanky guitarist but that does not mean you could have wrote the same album as good or better than a band originally did or capture the essence of the original. A lot of musicians have their own traits they have mastered & someone trying to replicate could fail regaradless how good someone is as a musician.
An album has a full band also.
I'd like to see say Eric Clapton or someone recruit 4 other guys and write an album like say Sentenced 'north from here', sacramentum 'far away from the sun', morbid angel 'altars of madness' or any opeth and see if it's nearly as effective. It does not matter how competent he is but style,influence,etc..
Regardless who is better a lot of musicians still would struggle trying to attempt writing someone elses material the way they did because they are use to playing a certain way because how they learned their instruments. It does not take away from them or others.
I know someone that has been playing guitar for 25 years but still could not write a good death album because he does not know technique of the style because he plays a certain way. Just like someone in metal might not be able to write a good bluegrass album or whatever.
The way you play your intrument is highly influenced by what you listen to. I play a certain way naturally & it's not forced one bit. I would suck at writing music in a different style but that does not take away from my playing or whatever.