> Are there really a significant number of people willing to buy a computer with no concern for the type of software it will be able to run?

Most common software that typical buyers use is available on Mac or Windows: Web browsers, office software, maybe an e-mail client.

This is why Chromebooks are a viable option, too.

Even my software development workflows are mostly cross-platform when I think about it. I can run all of my IDEs and text editors on my Mac, Windows, and Linux computers.