The oil hole likely is a good idea for HD applications. The lifter face would still need to be cut correctly, or none of these other tricks are going to help. DLC coated lifters is the same thing. What does the crown face look like when measured?

Many of these parts companies have been bought and sold and the shop guys who used to do these parts the right way have likely retired, or have been forced out by these big business mergers. They could have new people not fully aware that their work is off the mark combined with tools that are worn out so the accuracy level has deteriorated etc. etc. The first company who fixes this problem with better made parts and high level of quality control that keeps junk from getting shipped out is going to make a lot of money. The other companies who pretend crummy parts are not their fault will die a slow death.