iirc due to some anti trust lawsuits, they cannot do that anymore.

But it's still easy to coerce OEMs to run Windows because they offer stuff like quick support and standardized IT support.

If an OEM ships Linux, they don't want to have to make an entire department to help troubleshoot the OS for users who will inevitably call for help. Ignoring them would only result in returns and loss of sales.

I think some thinkpads actually do ship with some distro like redhat or opensuse as an option, but that's because thinkpads are very popular in the business space which means lots of CS people use them, so it helps save some cost from a windows license that won't get used.

Like I said though, if windows really dives into the deep end, I think a potential market would open and some OEM will take a chance on it.