I know of enough instances of using the schubek/tool steel type lifters on cast cams where the outcome was the same as yours that I'm comfortable in my assumptions that it had nothing to do with oil pressure.

There was a point in time where I felt this approach to solving the problems with flat tappet cams wearing out in street driven vehicles had some merit, but I've seen enough of them, and know of enough others, where I no longer feel that's the case.

As Oldiron stated, his motor showed no symptoms at all from this happening to his cam.
The motor was getting freshened, and it was discovered during tear down.
Since there is only "wear" at the nose of the lobe, and no wear on the lifters, it doesn't even change the lash.