Many of my older fly tying books show this type of tool for whip finishing a fly.
I know it works, but I think that the newer tools that let you do the knot without cutting the thread are certainly faster. Plus, if you do a 'double' it's much easier with the new tools.
The old way still has it's uses, though, but I'd not buy something that can be made for next to nothing from handy scraps, but I'm cheap .
AND, for those that want to make one, try using gel spun materials for the loop. Very slick and strong.
It Just Doesn't Matter....