Well, that's "you" Cab ... because you have a rack full of bearings to chose from. But take a guy who purchases a kit or whatever and takes it to an engine builder and says "have at it". Unless they do a lot of the same brand of motor its unlikely they'll have a rack full of bearings to chose from. And rather than dick around with buying and waiting for a set to show up that fits, they just line hone the block - which potentially ends up costing the customer less.