Matt..

As a songwriter, yes.Lou
reed is just fine...but we're talking about guitar players...as a guitar player Lou is clumsy and knows about 5 chords which he plays very badly..
Bob
weir is a journeyman guitarplayer with no outstanding skills or style..again, a very talented writer..but..that's not what we're taling about...

Nothing revolutionary or exciting about the playing from these guys..just like curt cobain and so many of the other strummers names being bandied about...

If you want to start listing great songwriters who play guitar, that will be a very different list...
Irving Berlin was one of the most successful songwriters in the history of the world!
He wrote everything in f#, just using the black kieys on the piano,,by your definition we would have to call him one of the "great" piano players..

All I can say is, if I'm putting together a band and I'm looking for "guitar players", I'm probably not gonna hire Lou Reed..now, if I'm looking for a writer and a singer as well then my choice might change.

Bob