Thanks Romullus, keen eye as always +1
It's really due to ease of access to the Megascans library. At one point I was looking for a tool to bridge Megascans into Painter and there was (briefly) one in development, but it never reached the market. I do use Painter, especially for map baking, but unless I need to hand paint some details, Mixer is much faster. Unfortunately Mixer does not currently support 8k export, which is an impediment in some cases.