The lifter and cam lobe DO 'match profiles' during the breakin, I supect the same could be said for the lifter bore and lifter. Thats why it's always imperative to mark your lifters on a tear down to get them back in their original hole. I've seen all kinds of different wear patterns on lifters.
Make no mistake, there were plenty of cam/tappet failures 'back in the day' for various reasons. It's the fairly RECENT failures from virtually ALL cam manufacturers that raised the issue a few years back. Even with good
oil and the right additives (now or back then) if you don't break it in correctly in the beginning it will fail.
Consider this: How common was it to find double springs AND a spring damper (THREE springs if you would) in the 60's? Pretty darn rare! Today? Pretty darn common!
Number one thing to do for a modern flat tappet breakin? REMOVE the inner spring!