That's actually a pretty substantial chunk of "the IT Industry" though. And if you're the people who make Windows, it's not surprising that it's a big enough chunk to do something about.

I personally find that the term "IT" has become a bit of a code word for "Enterprise Wintel", and that anyone working outside of the gravitational pull of Microsoft prefers to describe themselves as working in "tech"

I think that IT has become a code word for being a tech worker in a company, rather than a worker in a tech company.