You don't need to coat over an EPDM roof unless the woven backing material is showing through. That will happen eventually, but its not a routine thing. Until then keeping it clean is goodness, though probably mostly cosmetic. And it is not really necessary to use "rubber roof treatment", though it helps a bit with chalking (white or black streaks down the sides of the RV).
"Conditioning" is basically a wax job. EPDM rubber has a white powder in it to make it pretty, and it chalks off and runs down the sides of the RV with moisture runoff. A conditioner helps to prevent the chalking. Well, it binds the chalk in place to avoid the streaks. But its gonna loosen up and come off after awhile, which is why an annual (or better) cleaning is wise. If you remove the chalky accumulation and put on a conditioner, you might get a summer season without much streaking. You can use a liquid floor wax like Mop n Glo for a "conditioner", but the stuff the RV stores sell isn't real expensive either.
The "spot sealing", though, is critical. Somebody needs to check out the roof seams and protrusions (vents and such) and touch up the sealant around them as needed. May not need anything, but somebody needs to check. Sometimes the old caulk needs to be peeled back and replaced in places. The caulk can be repalced with Eternabond tape if you prefer, but it's just another way to accomplish the same thing.
2004 American Tradition; 2013 Buick Verano
Homebase in the Ocala Nat'l Forest near Ocala, FL