As others have said microsoft leverages their considerable relationships and other products to pump their cloud numbers. My friend who worked for an electric generator told me that microsoft offered to switch the electricity source of their data centers to their company if they switched their cloud to azure. That's on top of the O365 deal and of course massive credits.

Microsoft bundles on-prem enterprise office and exchange licenses into O365, so I think those numbers are misleading.

You only get a good discount on Microsoft Dynamics if you also get some cloud credits ... oh and while getting it: do you want the LinkedIn integration to Dynamics? LinkedIn is accounted for under cloud, too.

They can shift the revenue accountingwise wherever they want it. (Just have to make sure they internally track it better, to see which products actually bring the money ...)

creative accounting tricks will allow anything to be classified as "Cloud" revenue.