With high end chips like that it's often possible to get dramatically better efficiency by running it at less than peak power consumption, like 90% performance at 50% power or something like that. It's hard to compare the numbers in a fair way.
they didn't use GDDR cause they wanted the memory capacity which is really important for recommendation models. But I totally agree that this is a sort of perfect cost/perf per watt point for a home setup. I really hope they do it, if not for this one at least for v3.