Microsoft is losing Builders fast. They’re switching to MacOS and Linux. The biggest pull keeping people on Windows, outside of shear inertia, is content creation and gaming. However, even these are falling to Linux.
Without Builders, you don’t have software, and without software, you don’t have users. This is why Microsoft needs Windows Lite.
You wish.
Why bother? Just to keep paying MS?
What do you have to pay Microsoft for when using .NET?
Scalability was the primary reason. An application running on physical Windows-based servers can’t quickly scale up and down, leading to higher hosting costs due to everything scaled to maximum capacity at all times. Or, more often, leading to slow performance and lost revenue due to the customer not wanting to pay for maximum hosting capacity at all times. So the customers want scalable cloud hosting. And when losing a customer often means a loss of millions of dollars in revenue for my former employer, they want to keep those customers.
A secondary goal is increasing the speed of deployment for new customers. Scripting the entire environment - including servers, network, storage - can make it very fast to spin up a new customer or testing environment. That can be done without .NET, of course, but .NET Core is the obvious next step for a large distributed enterprise product suite that is (was) already running on .NET Framework.
.NET Core isn’t a primary platform for desktop or mobile client applications. It is very common as a hosting platform; that is likely to continue.