Don't etc really want to get shot down in flames, but as ever where there's a bolt there's a controversy. They have their place in protecting cliff top environments.
I took a stack of pegs out of Cornish cliffs about a decade ago (often by hand!) and almost invariably, whatever the head looked like the metal in the rock was in a worse state!
In reply to Brendan Hanratty:
alternately read he article and link to the original thread to see how your suggestion was discussed and avoid groundgog day