So for 1k more, you are getting a whole lot more and to configure the 2019 to similar specs would more than double the price of the base 2023.
Sure, the $7000 ASi MP has a far better CPU and GPU than the $6000 2019 - but that's not really the point. The point is that the $7000 ASi MP has
exactly the same CPU, GPU & RAM as the $4000 Mac Studio - moreover, even after you've
maxed out the CPU, GPU and RAM on the new MP, it is
still $3k more than a Studio
with exactly the same CPU, GPU & RAM. (& the only practical SSD difference is that Apple arbitrarily refuses to sell SSD upgrade kits for the Studio).
Nobody would have picked the base 2019 MP on the grounds of its "stellar" CPU and GPU performance. If you wanted that level of performance with 128GB or less of non-ECC RAM you could get it in an iMac for half the price and get a screen worth about $1000 thrown in. The point of the MP - and the argument for the $3000 mark up over a
faster iMac - was a Xeon-class processor* massively expandable RAM, ECC* RAM, and a huge amount of PCIe expansion
including a choice of multiple super-powerful discrete GPUs. In short, a lot of the cost of a base Mac Pro was paying for all those "Up to"s.
The ASi Pro has whittled that down to
just the ability to add
non-GPU PCIe cards and a couple extra TB3 ports (we'll have to wait and see where Apple have managed to magic up a bunch of extra PCIe lanes from and what the actual bandwidth of these slots and ports is really like). No RAM beyond 192G, no
more than 24 CPU cores, no more than 72 GPU cores (which need ASi-optimised software to deliver).
Yes, there's a sub-niche of the
already niche 2019 MP who need PCIe expansion for specialist a/v cards, super-fast networking and extra storage - and a
sub-sub-niche of those for whom external Thunderbolt won't cut it (even though that's come a long way since the Trashcan days). That's the market for the 2023 MP, and I'm not going to speculate whether those people think its worth the price. Trouble is, though, I think Apple are counting on that sub-sub-niche being so locked into MacOS workflows that it's cheaper to pay $silly for a Mac Pro than face the HR and downtime costs of switching to PC or something in the cloud.
However, its really no skin off Apple's nose that Apple Silicon isn't brilliant as a Xeon/Threadripper-killer - because it's doing just
great in iPads and MacBooks that sell by the shipload, its pretty central to the $3500 ski goggles (which Apple clearly see as the next halo product to succeed the iPhone) and scales up well as far as the Studio. The "powerful personal workstation" market is probably shrinking rapidly, being eaten by increasingly capable laptops and SFF systems at one end and "pay for what you need when you need it" cloud solutions at the other.
(* I'm not sure if "Xeon" or ECC are
relevant to Apple Silicon but they were absolutely 'premium' features of Intel systems that formed part of the justification for the price difference c.f. Core-i, non-ECC systems like the iMac).