There is a fear there. Ask any engine builder. I don't run flat tappet cams in my engines at all, unless they're requested by race rules, then they get either a nitrided core, or EDM/ceramic/tool steel lifters.
I can think of two builders right off the bat who have wiped lobes off of brand new cams in the past year. These are builders who have been building for decades and are very cautious, following every single step.
I don't take risks like that, especially with a customer's engine. If a cam fails to break-in, you're not only out the money for a new cam/lifters, but you're probably out the money for tearing the engine down, replacing the bearings, oil pump, etc.
Even when cams are broken in on a machine, there's not a guarantee that you can just install them and walk away. I can think of at least two instances, on the FE forum, where cams have been lost after they have been "broken in" at the cam grinder. The machine they use can't simulate every load that's present inside a running engine.
A roller cam is a 99.99% care free fire-up. No maintenance, no special oils, no leaving out inner valve springs, no rain dances, no voodoo dolls. For the extra money, it's cheap insurance.
I wish I could take all that you have written, smile, and feel good about the world, but you can complete every single step that you listed (and more) and still wipe the lobes clean off of a camshaft.
Since I'm sorta the "newbie" on this particular forum without a lot of street credit, feel free to ask the thoughts of other builders....Keith Craft, Barry Rabotnick, etc, etc.