"One often hears that “band X is a ripoff of band Y.” Band X need not have covered any of band Y’s songs—all they have to do is “sound like” band Y. This has always struck me as something of a silly critique..."
Although this is not generally what real music snobs complain about. Hip-ish indie bands frequently rip off other, older hip-ish bands. To wit:
"Fell in Love with a Girl" by the White Stripes rips off "Search and Destroy" by Iggy and the Stooges in that it essentially lifts the melody of the outtro wholesale
"Connection" by Elastica rips off "Three Girl Rhumba" by Wire in that the exact same chords are used in exactly the same rhythm
"In a Young Man's Mind" by the Mooney Suzuki again lifts wholesale from "Kick Out the Jams" by the MC5 (though every MS song rips off something older, and they freely admit as much)
I really think it's an instance of T.S. Eliot's dictum "mature poets steal, immature poets imitate." Good bands are constantly making allusions to other things the listener might be familiar with (much as, for example, Dante's Commedia reads a lot better if you're independently familiar with the people it mentions). The problem with Creed (well, one of the problems with them) isn't so much that they sound like Pearl Jam, but that they only sound like Pearl Jam--there's no real attempt to do anything above and beyond, which is what makes "Fell in Love with a Girl" and "Connection" great songs in their own right, and makes "In a Young Man's Mind" a facile attempt to recreate the original.