You actually still could. There were plenty of non-Windows OEMs back then (SGI, Apple, and Sun are examples; all of them built desktops/workstations without Windows installed (instead using IRIX / Mac OS / SunOS/Solaris, respectively)).
You are technically correct (the best kind of correct), but Apple had a very small (and shrinking) market share. Where I lived (NZ) they were almost impossible to find - very few shops even carried them and you paid a large premium. SGI and Sun built specialized, expensive machines for specific professional markets and didn't really compete with Microsoft.
In 1995, if you walked into a shop and said "I need a computer" you were shown a range of machines, all running Windows. It was hard to buy a bare machine without Windows unless you built it yourself. Various PC OEMs made noises about offering other OSes (or even creating their own) but Microsoft shut them down with licensing clauses.
The court cases eventually had the desired effect and now OEMs are free to offer Linux and ChromeOS machines as well as Windows. Took a long time though.
You actually still could. There were plenty of non-Windows OEMs back then (SGI, Apple, and Sun are examples; all of them built desktops/workstations without Windows installed (instead using IRIX / Mac OS / SunOS/Solaris, respectively)).