Originally Posted by
Sturmcrow
That's not entirely true. Cones are case hardened, so grinding off the hardened outer part is going to make them run smoothly for a short time, but they'll wear out a lot faster.
The key word is "maintenance". Cones get pitted by lack of grease and water infiltration, which causes them to corrode.
I have ridden grinded cones for many thousands of miles. They're still like new.