Well, you obviously do not have to pull of the sprocket from the magneto axle when setting the points. So the taper fit stays in a good condition.

But on the other hand, I have never had a worn out taper just from taking the sprocket of.

And at 174 URO? No way! I guess it is just one of those designs that did not catch on and is now wanted for shere rarity…

Cheers,
Erik