For heaven's sake, you never call someone's voice their instrument. Ever. The terminology is nonsensical. Again, the box just does not fit.
To be fair, as a music student and vocal major in college for a time, our voices were consistently referred to as instruments.
No clue if it's widespread, but it's not as nonsensical to me as it appears to you.
The problems these bioboxes are causing are very widespread. You simply cannot twist the article beyond all boundaries of accuracy, correct terminology and common sense just to fit an infobox. Infoboxes are supposed to be a means to an end, not an end in themselves.
What's frustrating the most is that the boxes don't break if you fail to include information. So no one ''has'' to put something for country of origin or instrument or party or anything else, and the box is still good.
There are constructive ways to deal with things, folks. I'm not directing this at who wrote what I'm quoting, but it seems like, more and more often, the path of least resistance is being ignored.
-Jeff