Pictures sent from a computer at a phone, the From My Mac pictures, are not "owned by Photos, and they're not fully under Photos' control. They can't even be deleted or edited, for instance, but must be managed through the Mac's Finder. The idea for this pre-iCloud system was that these pictures were just for temporary viewing on the phone.
iCloud Photos is the method we use to fully share our pictures among our Macs, iPhones, iPads, etc. I have no clue what you mean by, "iCloud sync “forgets” faces." It works fine for me. Not exactly the same, but for my son-in-law that I just looked at, I have 376 on my Mac and 378 on my iPad-- pretty close when I've been working with the pictures today. iCloud is a true synchronization, not just a transfer.