Are people so stupid that they don't know that about 80% of these "live" performances are lip-syncs?
I caught the tail end of the Orange Bowl halftime and there's some group, who I have never heard of, prancing around on stage pretending to play their guitars, which aren't even plugged in, with the singer "off" ever so slightly with the lyrics. So obviously lip-synced.... but I guess what does it matter to their fans who appeared to be dominated by 15 yr old girls and who likely don't even care, much less spot the obvious.
Face reality, likely half of these "popular" groups of today release albums which are actually recorded with studio musicians providing the actual "talent" and who "augment" their performances with prerecorded material to cover for their deficiencies as musicians.