[pitay]

Microsoft could just not give discounts to computer suppliers that don't have UEFI secure boot on forced on.

I definitely recall Microsoft killing hardware manufacturers putting Linux on the machines that they sold by mandating that if they put Linux on any consumer desktop they would not get the OEM discount for a Windows licence for any computer they sold. It stopped new non Windows PC sales dead at the time IIRC. This was something like over a decade ago.