Squirt hole or no squirt hole?

I always thought that most modern flat tappet cam failures (not counting over-springing them) were due to the lack of enough zinc in todays engine oils. Is that not true? Is it really lack of oil splash?

That's why it's a theory.
They came out with the roller lifter, no squrt hole, thinner rings, and less zinc, - all bout the same time.
So it's a proces of elimination .