You mean we can't have a check-box on the PC vendor's web page where we configure our device, which lists several operating systems?
You can. But people will freak out when that checkbox would say "Linux + $80". They would think "But Linux is free". While it is a free OS, the OEM wouldn't get subsidies from bloatware providers which help subsidies the cost of the computer.
But folks don't even have that choice. Where we are now is a product of many years under the restrictive MS OEM licenses, and a whole, bottom feeding ecosystem has developed to exploit it. That has done a great deal, IMHO, to limit the innovation and development of alternative OSes, both free and commercial. What is more, in the absence of the predatory MS OEM licensing, as time went by, those self-same bloatware vendors would subsidize other OS' as well.