The debate will never end but, CNC made hubs adapters are the way to go for all us amateurs. Very few have the know how and the time to get a rag joint aligned and realigned again and again. I have used both. I suspect, many old school pro rag joint guys have never tried or installed a CNC hub combined with a engine mounted spring chain tension er.
I wish they would give this new system a try, I am guessing they would probably never use a rag joint system again. Self aligning CNC hubs combined with a engine mounted side, skateboard wheel style spring tension-er keeps our amateur drive lines trouble free, very noise free, smooth as butter and extremely reliable from the very start. Its something anyone can do, plus they are not very expensive. This system also helps take pressure off the hub from over tight chains, another cause of bearing and hub failure and heat. Note: The spring tension keeps a gentle pressure on the chain so the bearings are not being over taxed. combined with a centered hub and one that is not wobbling to and fro, making a chain over tight and then too loose.
Having a chain seize up, derail or a hub fail is potentially dangerous also. Yes, I would probably trust your rag joint install 100 percent crassius... but not mine. I agree, yes if one doesn't pack lots of new good quality grease into a dept store bike hub, it could overheat and fail. Zero fails here with a greased up hub though.
I also always add front and rear pull brakes and never use the coaster brake, as coaster brake mashing at 20 mph can cause the cone nuts to become out of adjustment in bearing pressure, leading too premature hub failure also. Many times people on this forum say what can happen but never say what will prevent the problem or totally explain why.