Patching Single instances in 12.2 and up

Afternoon

     We have a fairly small oracle foot print, no racs nothing funky, we have 7 or 8 stand alone database instances varying from 11.2 through 12.2.  We are about to start taking the plunge into 12.3  (18c)  and I just started fooling around with patching and noticed I can no longer patch through OEM.  Reading up I see fleet maintenance is the direction oracle is going.  Most of the documentation focuses on patching racs and having some sort of central fleet maintenance server which stores all the gold images and what not.  From my understanding is this isn't strictly