Every tool has a job it does best, many jobs it "can" do, and some it simply is the wrong tool to use. Table saws excel in ripping, where a good fence and work support are important. To do miter cuts or cross cuts on larger length pieces and in particular compound miter cuts, they begin to have problems. OTOH, a RAS fence and table layout are perfect for crosscutting long pieces that don't exceed the capacity of the saw in depth. With effort and excessive time setting up, they can be used even as an overhead router or planer, to some small degree. Ripping with a RAS simply is something I don't care to even try. Miter cuts involve having to crank up the arm before swiveling the arm and then trying to lower it enough to cut the stock, but not really gouge into the table too much.
That's where the dedicated miter saw comes in best. It can be tilted and swiveled with the press of a lever, usually and makes rock solid cuts with ease.
In my old shop, I had a RAS built into a bench, so that the blade was in the "middle" between the walls. I could crosscut to the center of 20' material. To the right of the RAS, about a foot beyond the swing of the arm, I had a recessed area on the workbench that held the miter saw, so that the table of the miter saw was flush with the workbench top, which was also flush with the RAS table. It was a snap to slide the miter saw forward in its trough to align the saw's fence with the fence of the RAS, using stops on the trough to instantly align the frame. Since it was off center, I didn't have quite the length capacity, but it was never a problem. It was very easy to crosscut a piece to a length with the RAS, then move over to miter the other end on the miter saw.
No saw was "best" or "worse," saw in the shop. Each did its own job well, with an eye to convenience and accuracy as the goal.
Micajah