FT cams are cast iron based, same hardness right through & can be ground to any size.
 Roller cams such as the 8620 core, commonly used, is steel & is hardened only to a certain depth, & that limits lobe lift, LSA, etc.
 Experienced engine builders have experienced FT break in failures so there ARE cam & /or lifter failures.
 There ARE soft lifters. I had a cam fail with lifters that came in a Crower box [ Crower do not make lifters ].