The most well-known use-case of the Mac Pro is in video editing. Famously, Pixar use Macs Pro to render their movies, so being able to install GPUs is essential. The MP23 doesn't support extra GPUs, either via PCIE or Thunderbolt, so what exactly is the point?
Let’s just say you had a bunch of Audio and video capture card that are pcie. If you wanted to use thunderbolt you’d end up buying multiple pcie to thunderbolt enclosures, have to deal with thunderbolt cables, power cables for the enclosure, and making sure it all is reliable. If you had 3-4 cards that could end up being a mess of wires.
Mac Pro isn’t really targeting normal consumers. It’s a high end product for media professionals. Big companies have budgets for this stuff and professional workstations are expensive regardless of brand.
It certainly feels like a legacy concern to some extent though. Like the trashcan Pro was exactly what it needed to be, but people weren’t ready to shift their hardware out to Thunderbolt just yet. Perhaps the next generation of Mac Pro will return to that form factor.
I wonder if there is really not a need for a MacPro at this point, but if they scrapped it, people might thing the ARM chips are not up to the challenge of being a workstation.
Being generous, it's possible that to be able to use the PCIE cards that are compatible with macOS over Thunderbolt, it would end up being more expensive to use a Studio. But yeah, given that Studio and Pro are benchmarking at pretty much the same, it seems like a no-brainer to go with the Studio.