Unofficially, you can do it yourself.
https://everymac.com/systems/apple/imac-pro/imac-pro-faq/ima...
Also there is a big difference between “it can’t be done” and it “cost more than I’m willing to pay”.
That is the question and their mode of business. I am not aware that they are required to perform work on random Macs brought to them and they are pretty scarce. Which brings us to point #2:
Also there is a big difference between “it can’t be done” and it “cost more than I’m willing to pay”.
Yes, it is better than "it can't be done". But it is a strong limitation of a computer, if the pure work price for exchanging a memory module or a SSD is $300. And requires to find a service center which can do the work and probably a longer stay there. Even on most laptops, such actions are a matter of a few minutes, and on most desktop even much faster and normally user-doable.
> The iMac Pro clearly fits the needs of 99.9% of people who need some horsepower in their work - video editing, pro photographers and coders who want a ton of VMs or whatever.
The entry-level model is $5,000 USD, RAM can't be added later and there's no option for an NVIDIA video card.
Even in rich countries, that's clearly not what 99.9% of people want in a desktop computer with "some horsepower".