The point they were making is that a Windows user generally (Hackintoshing aside) can't just install MacOS in their existing computer; it requires purchasing another, Apple-brand computer.

As in - if you already have a windows PC and someone says "you should try a Mac" you can't just install MacOS, it requires you to buy a whole new PC from Apple. With Linux you can at least just install it in a second partition and use it that way untill you're sure it works for you, zero money required.