My wife is putting an 8' long piece of granite on the counter in our master
bath.

The granite guy says we need to provide a frame for support under the edges
of the granite.

To my hard old head, it seems to me the best thing would be to provide a
smooth, flat bed for the granite to rest on. This would seem to be a much
better support platform, as it would give support under much of the surface.

The edge frame the granite guy wants us to use seems like it would invite
the granite to eventually crack where no support is.

What's the deal here?