I've noticed it as well. I suspect it's from the Windows universe where it's common to snip a bit of the screen which isn't pure text when asking about some problematic GUI thing which is causing problems.
I've never been a Windows user, but at my current job, Windows is core to just about everything, so I am forced to use it for a lot of stuff (Outlook, SQL Server, Excel, etc). I see lots of screen snips flow around, and even use that technique at times when asking our help desk for some mystifying Windows thing. Skip -- https://mail.python.org/mailman/listinfo/python-list
