My use case for Paint is highlighting one off screenshots for clients and the like. Nobody is going to send your sort of screenshot in a professional environment, it looks like it was marked up by a kindergartner.
My workflow: I open up snipping tool, take a screenshot, copy it, paste it in Paint, mark it up quickly (arrow tool or circle/rounded corners tool usually), and either save it or (usually) copy it and paste it into an email or Word Doc. Super easy and quick, I can do this in the time it takes GIMP to load or another program to download, its also always there. I do this on a monthly basis at least.
I've never had to do anything more advanced.
Though if I ever need "advanced" screenshotting I'll keep this in mind.
PS: If you actually do the same thing in paint they have a lot of useful shapes and you get a preview of how they look. Which is nice if you don't want the chicken scratch look.
If i need to do something well, then I use Paint.net (which is best parts of Paint and Photoshop combined in a free and super fast package).
If I need something quick, then I can use the snipping tool.
I literally have not turned on paint ever since I discovered windows snipping tool and paint.net (which is couple of years now).
Workflow is generally Screenshot, crop, highlight with text / arrow / circle past into email. Paint.net is useful, but not on every windows box and often not worth the download when I 90% of the time I just want to send something to a coworker who might email it to a customer.