Last week, I had a party gig. We use different guitar players from gig to gig, and I noticed that the guy we had that night was using a capo on his electric guitar. Since I use an Bb single row, and an F-Bb-Eb triple row, many of the songs end up in the key of F. Not surprisingly, the capo was on the first fret. I did not notice any ill effects from the use of a capo on an electric.
I can't recall any other electric guitar players I have worked with using a capo, but I don't have a problem with it.
Hasn't Keith Richards always used a capo on his guitar? I remember the first time I noticed it, and I think he had it up pretty high on the neck - like on the 7th fret.