Just like Word's doc format?

It's only a 'standard' for those closed-minded industrial drones who won't ever contemplate using something different. This is the attitude that causes awesome, innovative software to disappear beneath a morass of "But it's not industry standard!".

I create graphics. I don't use any Adobe software. Adobe isn't the only graphics software company out there.

Sure; if you can say "industry" in reference to a bunch of people whose employability is hinged to a single PC/Mac application.

Not merely a single application, the entire network of Adobe applications, and the interoperability between them, which doesn't just mean still images, but audio and visual effects in commercials, film, video games, physical print, professional photography. Almost any visual media outside of the browser at some point interacts with Adobe and PSD files.

And someone whose employability is probably tied to a specific OS, toolchain or software stack really shouldn't throw stones.

What percentage of professional graphic artists do you think were using non-Adobe products through the early 2000s?

I don't know for sure but I'd wager upwards of 80%.