Having read the actual detailed article what seems to be happening is that some customers buy "on-premises licenses" without mobility rights, and MSFT used to let them use those licenses on outsourced hardware. But people were using those licenses to just put their deployments on general cloud services- which is not what the license was intended for. The license was intended for fixed, outsourced bare metal hardware.
Basically, MSFT is just catching up to the fact cloud services exist and you're going to need a specific license if you want to run the software on the cloud. Now, apparently this author finds this surprising, but given that the license he's complaining about is an "on premises" license it sounds more like MSFT were being generous by letting customers use the licenses on outsourced hardware, and never intended it to be carte blanche for running your "on premises" license in the cloud - which is very obviously not on your premises.
What it sounds like is happening at the moment is Amazon is running a shit tonne of MSFT software without any MSFT licenses. Which sounds pretty cheeky to me.