Before that was the pre-trash can Mac Pro in 2006-2012. So that was canceled most of a decade before the 2019 model.
High bandwidth PCIe hasn’t been a thing in Apple world for most of 15 years.
Also Thunderbolt is trivially disconnected, which in many critical workflows is not a positive, but an opportunity for ill-timed interruptions. Plus I don't have to buy a fucking dongle/dock for a real goddamn slot, make room for external power supplies, etc.