In the old days when I owned a custom cabinet shop I always cut dadoes and rabbets using a large table saw with power feed and a quality dado cutter. The results were excellent, especially with dadoes because there was no climb cut as with a router.
Between selling my first large cabinet shop in 1996 and getting back into the cabinet business in 2006 safety laws had changed and I no longer could use dado cutters on table saws.
I had a TS55 and several guide rails. I also had an OF1010 plunge router with the sliding guide rail adapter in addition to the LR32 system. My approach was similar to the suggestion by StephenB. I made the inside cut on rabbets with my TS55 to ensure there would be no tear-out. Then I cut the rest with a larger than needed bit using the OF1010 on a guide rail, which did not need to be precisely set, because it was the saw cut that was important. For dadoes, I made cuts with the TS55 on both sides. Then I would finish the dado using the OF1010 on a guide rail and an under-sized bit, making a second pass if needed. I always made the right-side saw cut first and used a spacer jig I made to move the rail to the left the exact amount. It might sound like a bunch of trouble but I make custom cabinets and the time necessary to make quality joints is calculated into the quotation.
Between 1996 and opening my new large shop in 2010 I often rented space in the shop of a pal who owned a radial arm router, where the router comes down from the arm. Rabbets were simple, so long as the direction of the grain was respected. Clean dadoes were made using an under-sized bit, small enough that when the router was moved appropriately for a clean cut on one side the tear-out on the climb-side did not reach the good side. The work would be slid over and the final pass was made in the opposite direction. I must say this method is faster than making two saw cuts before using the router. However, not all that many people have radial arm routers.
Personally I have not used rabbet bits with a guide bearing in decades since the actual thickness of even cabinet-grade plywood varies from brand to brand. I also have never liked using a conventional edge guide because at the end of the cut the bit can slide into the work, which is not the case using a guide rail.