I guess you'd call him a "a welder so huffed up on his own farts that he'd forgotten that the stuff he welds might also do something useful in addition to beind made of the metal and tools du jour".
The rest of us would realize it's not targetted at consumers of welded goods, but as a discussion or example for other welders. It's not something to be mad about, it's perfectly reasonable that welders talk to each other about welding, and sometimes weld things for fun or practice or to show off to each other.
In the world of programmers, we like to do the same thing. Most of us work either on something targetted at people who want marketing and handholding about how to use the product or on something so niche and that it's really only useful to other devs (and mostly the only devs its useful for are a small subset from the first group that work at the same company) - and we often charge for that kind of work. When something's on github, there's a high likelihood it was made by a programmer wanting other programmers to see it for one reason or another.
> I get that this is probably some kind of personal project, but I see so much of this nowadays and it really boils my biscuits.
This has been common since the late 90s when I started paying attention to programming things, and people weren't calling it a new trend then...