One thing that the Mac Pro has that a list of components won't show is just how nice (and expensive) it looks and feels. The case is milled out of solid metal, the internals are all clean and cleverly designed and the thing runs totally silently. The extra money (at least to some extent) does go somewhere.
Which is all fine and dandy - the problem is that Apple doesn't offer any more affordable options if you want a regular, desktop system that lets your choose the displays you want and add a bit of internal expansion... which is something that Apple
used to offer before they doubled the entry price of the Mac Pro range ...and that's for the $6000 base configuration that really doesn't make
any sense until you spend another $10k+ on expansions that actually need all that PCIe and RAM bandwidth.
If you're buying a computer, what matters is
whether it suits your needs - not whether it can win a game of Top Trumps against the Mac Pro or if it has no visible cables inside. If you insist on only comparing with a PC that matches the MP spec-for-spec (especially on PCIe and RAM capacity and "only Xeon will do") then, yeah, pretty soon you're into MacPro territory and it's mostly down to prices of high-end Xeon Ws, workstation GPUs and terabytes of ECC RAM.
The MP's problem is that there exists a huge choice of PC kit in the $2000+ range that is more than good enough for the many people who
don't need
eight high-bandwidth PCIe slots,
don't need 1.5TB or RAM
or the expensive Xeon that can access that much (with Apple's 24/28 core options you're paying thousands extra for the M-prefix processor to get that extra .5 of RAM capacity)... then at the other end of the scale there are 56 core Scalable Xeon systems, not to mention whatever insane number of cores AMD are offering today and
proper server style systems (with lights out, redundant PSUs and - oh yeah - non-afterthought rack-mounts that
don't put the RAM slots underneath!).
Also, some people can't stomach Windows or don't want a liquid cooled RGB-lit monstrosity in their home or workplace lol.
I do prefer MacOS to Windows, but the inconvenient truth is that (a) MacOS ain't perfect (go read the Catalina and Big Sur forums) and (b) Windows stopped being a kludgey DOS shell years ago and millions of people get their work - including the sort of "pro" content creation that the Mac Pro is aimed at - done on Windows every day.
I suspect that the only people giving the Mac Pro a second look are those who are so committed to a MacOS workflow that it is cheaper to pay a small fortune for over-engineered hardware than contemplate changing. Which is a good way to extract more money from a pool of "loyal"/locked in customers in the short term. In the longer term, though, if the response to people who criticise Mac hardware is:
Enjoy your windows box...
...then that is going to be a rapidly shrinking pool as more and more people take that advice. That ends with no more Macs.
Hopefully, Apple Silicon will mean that instead of, basically, just pushing standard PC hardware with modest specs running an alternative OS (in nice boxes), Apple will once again have a unique hardware offering with an innate advantage over generic PCs. The M1 is certainly a good start - you can't really compare an MacBook Air to a Dell XPS 13 any more - so we'll see how that works out with the higher-end machines.
Who knows, maybe that half-sized Mac Pro in the leaks will also be half the price - which would still be a pretty expensive system but, if the M1 benefits scale up nicely, worth the cash.