Nasty Surprise

[Fazerider]

I think anyone who does that is just taking folklore as fact.
Provided the welder return/earth clamp is clipped on as close as possible to the weld area, it isn't going to induce troublesome currents in any wiring far enough away to avoid weld spatter. Even if it did, having electrically robust components like the battery and alternator there would actually help delicate bits like the ECU and instrumentation survive.
Mine certainly didn't suffer any problems, IIRC I stuck the clamp on the sprocket itself.