Nothing to do with anything being black magic or anything. A good quality welder will with good quality welding rods produce a good quality weld to a coded standard, even to X-ray standard. Something a cheap nasty welder won't do. But if its for something that doesn't matter to much, then fine but for something structural thats a different matter
That`s just like me condemning a slated roof done by an amateur....yet a lot that I`ve seen can still keep water out. You`re protecting your trade. A cheap nasty machine as you put it can still produce safe welds in the hands of a capable welder.......if he can be bothered.
Alex