The Adobe Suite, which accounts for the work of a LOT of Apple users has some significant issues on AMD. Not that they couldn't/shouldn't fix them, but it's Adobe. This is probably a very large part of the issue. Beyond that, they're using custom board designs that have significant lead time, and changing platforms isn't easy for an OEM.

Not talking down about prior motherboards, but the next run will have some very high end designs and features compared to prior gen Ryzen as well. I'm really looking forward to upgrading in September/October. Looking at a 3950X unless a more compelling TR option gets announced before then.