That and "Crumb" are a couple of films that convinced me that some people just are artists. It's not ego, or some desire to be eccentric ... they can't help it. They live "the art life", damn the consequences.
You could handily list any number of other people (John Waters just came to mind).
Similar to the author of the blog post, I have sort of demurred when asked if I was an artist. Partly it sounds arrogant to say, "Why, yes I am."
Partly it seemed to be a thing in the eye of the beholder. "I don't know, do you think I am an artist?" Plenty of people don't think Andy Warhol was an artist, Jackson Pollock....
Sometimes I have treated "artist" as a profession. Do I get paid for my art? Why no, I do not. I get paid for programming. Although when I write a game I am both programmer and "game artist". (Or is perhaps designing an elegant API for a framework a kind of art form? Okay, maybe not.)
If an artist can be a hobbyist the way many of us are amateur musicians, woodworkers, cooks, mechanics, (construction contractors), in our spare time then, yes, many of us are artists.
I think the older I get though (and maybe the more films I see about artists) I am slowly coming to accept that, sure, I'm an artist too. Just maybe not a very good one.