I guess a problem with that argument could be one displayed with the exact example in this thread.
What if; The Stooges were your favourite band ever and you held that opinion (you posted in the link), but then one day you found out that there was a band around 5 years before them that they completely ripped off, they even had a drug filled front man throwing himself about the stage like a nut. Would you suddenly not like those Stooges songs.
I'm really interested in music conceptually as well as sensually. I have two sides to me in that sense. I love exploration of sound and composition, I listen to a good deal of (what I believe to be) original artists and experimental artists and I don't limit myself with sound even though I get periods of researching particular genres to a more in depth level, but I also love a good dose of punk rock/hardcore sometimes, where there are plenty of rip-off bands I love. I just enjoy their songs and have fun listening to them.
Perhaps sometimes too much importance is put upon what are just songs. When playing music in bands was originally invented as a concept, I can't imagine those people thinking; one day people will get paid lots of money to write about these songs we're playing and people will get into raging arguments about what we're doing here. It was a communal activity and entertainment, a sensual and enjoyable experience like eating ice cream. It's nice for me to have a balance there and at the end of the day I don't know if a piece of music is very original or not because I don't have the hugest knowledge of music history, I just have to enjoy what I enjoy and not concern myself too much.