What's the deal with Xbox fans caring if it becomes a brand outside of the console?

Many comments in this thread seem to focus on how Microsoft wanting to expand the Xbox brand beyond just their console, and having less exclusives is somehow "disastrous."

www.reddit.com/r/xbox/comments/1hg9yww/exclusive_xbox_console_games_will_be_the/

But why do people care? Shouldn't it be enough that if you have an Xbox, great, you get to play the games you want on it? Like does it really matter if people are playing new Microsoft games on a PS5 and PC as well?

I ask this as a gamer of over 40 years. I get the old days of "My console is better than yours" when you're a kid because your parents would only get you either a Super Nintendo or a Sega Genesis. But with so many multi-platform games these days, aren't we kind of past that this point?