I've done a lot of pipe fitting and some plumbing as well as sparking, but I'm only qualified as a spark. Im nowhere near good enough to be a plumber, but I'm a reasonable pipe fitter. And there is a difference. I know my limitations but I'm always willing to do something new.
As for sparks not welding, when I carried out my training in the Royal Engineers, we were taught how to silver solder and how to braze and arc weld. All good skills for spark, although rarely used nowadays I'd still be happy to solder lugs on if I needed to, but with modern compression tools I doubt I'd ever need to.