In the EU, at least one of the problems is regulatory/tax for digital services. They need to charge you the VAT rate for the country where you are based. For that, they need two pieces of evidence about your location. There are various things they can use for that -- telephone number, IP address, card billing address, and so on. If they can collect two that indicate the same country, they're safe -- but if all of them point in different directions then they could get in trouble during a tax audit.

Of course, for larger transactions you'd expect that a human in the loop could work with you to get the right info so that they would be covered. But I guess for Microsoft, their definition of "larger" might be more than a few grand...