Groups like RUSH use sequencers and recorded tracks because there arent enough members and Geddy cant do all that fancy keyboard playing.
He used to, I think. In about 1981/82 when they were doing the Moving Pictures tour, he would sing, play bass, bass pedals and the Oberheim - although not generally all at once, and often he was just triggering sounds, like the sweep on Tom Sawyer. 'Course then MIDI came along and they started to use sequencers instead.
That I would have liked to have seen. The only time I got to see them was in 2004, and of course it was mostly automated by that point. Still fun though.
I also saw Rick Wakeman in 2000. He generally played lead - sometimes accompaniments at the same time - but he had a CD player or suchlike for the backings. Not that I'm complaining.
I don't have any right to complain anyway, because everything I have done was programmed except for the vocals and a few odd things like spoon solos, tape manipulation and 'playing' the echoplexer feedback.
It's one of the main reasons I've never seriously considered doing a gig, because all of it's preprogrammed. Of course there would seem to be a market for that now. On the Waldorf list I heard of a gig where someone just took in a laptop. That was it. They just sat in front of it, playing minesweeper for all we know.
If I ever do try a gig, the plan is to bring a bunch of gear, have some kind of video projection or other diversions in an attempt to give people their money's worth. And use a different version of the song to the album version. But I'd never try to hide the fact that I wasn't playing.