Phoney performances rampant?

Yes.

Honestly though this is pretty widespread at tons of levels of music. Studio production has become so easy and portable that a lot of tricks normally associated with recording have made their way into live sound. You'll even see relatively low level touring bands have some vocal effect processing going on. And I'm not talking about obvious like T Pain style autotuning where the effect is intentional, but just general autotune that the audience isn't even aware of. Tons of drummers at that level play to click tracks and in a lot of cases the band's light show and patch changes will be completely synced up to that. This is without question occurring a almost every arena level show you go to and making its way into smaller and smaller shows every day. Now not everyone does it. There are certainly bands and even entire genres opposed to it, but it is becoming common place.

In these huge events, like the Superbowl or performances at the Grammy's, a lot of the time the vocals will be live, but processed, with little else actually happening on the spot. The came about because it'ssoeasy to spot lip syncing and in a place like a football stadium its very difficult to stay on queue with how sound bounces around in a venue that size.

I don't know how this works from artist to artist. I certainly thought it looked like Tom Petty and Prince were actually playing during their respective performances. However, its certainly easy to sing live and fake instruments while making it look real. I just don't think RHCP gave a shit.