And more PCIe lanes, compared to the consumer platforms with a measly 20/24 (which is basically one GPU and one NVMe full bandwidth).

How is the ECC support deficient on later CPUs? I checked the docs, it does seem to be supported on the 7000x series.

The CPU is alright, but the motherboards are lacking. You can install ECC memory modules on them and the system will boot, but you don't know for sure if ECC is really working unless the motherboard reports memory status like how many errors were correct. Someone mentioned on HN that there's a Linux kernel component for this and that he had luck with an ASRock motherboard.