This is a subject that always gets in everyone's craw. Doesn't matter which forum we're on, whether it's an FE forum, Cleveland forum, Windsor forum, etc., there are guys on there that gasp at the fact that guys assemble engines differently than how they were assembled when they were new.
I don't mean anything against anyone at all, I'm just stating that if you choose to not leave those parts in there, the engine will be just fine.
Doug, I always read what you say very carefully, because you are one of the guys on here that has knowledge and experience to back it up. I will say though, that the only way I see the rocker tins being anywhere near essential, is when the drains in the heads are packed full of sludge and the oil can't get back any other way. Otherwise, for a new build, or someone bolting on new rockers, etc., they can be tossed.
I also hope that your first line wasn't a dig at me, as I didn't understand what it meant. If it has something to do with my timing cover leak line, I will say that I've had customers come back after years and tell me that a valve cover gasket was weeping, or an oil pan gasket on an aluminum block leaked, but I'll still stand by my statement that (to my knowledge), I've never had a timing cover seal leak. I do use a fixture to install timing covers, make sure the seals are lubed up well on first startup and always use a new balancer spacer. Maybe I was born with it. Maybe it was Maybeline.