You may not like it but I agree it shouldn't be illegal. If competitors aren't happy they can make their own OS.

At this point can you make a custom task manager and sue Microsoft to propose users to install your task manager on first boot? What about background image providers, why doesn't Microsoft propose to install background images from them at first boot?

It's an absolutely ridiculous idea.

They should not block alternatives, but having to promote them is complete nonsense.