Because they are too limited. You can use a solid roller lifter on a hydraulic lifer cam profile and get much more performance. Just lash them where I posted earlier and drive it.

I was big on the HRT a long time ago. You can't use much spring pressure. Most guys don't run near enough oil pressure for HRT's.

I don't get why oiling the lifters is an issue. Solid rollers splash lube. You can plug the oil off to the lifters and stop the leaks.