> GP probably means that while these pioneers might be aware of, might have tinkered with the nuances of processor design and syscalls and nitty-gritty details of TLB's and interrupts and stuff that, say, a kernel-level or SSD firmware guy might deal with regularly, it's highly unlikely that they would know their way around these like they know their way around the algorithms that they deal with on a regular basis, which exist at a much higher level of abstraction.
I think you missed my point. What I'm saying is there's a world of difference between "X knows B better than A" and "X doesn't know A [very well]". When you're talking about world-class experts who are at the forefront of research in their fields, if you work in the same discipline, there's a pretty damn good chance they're more of an expert at your work area than you are. (I'm obviously assuming "you" here are not the world-class expert in your area. "You" are just a generic but respectable engineer in your area of work.)
I think what you (& the OP) need to realize is that there's a HUGE and crucial difference between being, say, "rusty" on something (e.g. because you're not doing it on a day-to-day basis, or because it's someone else's system and obviously you can't magically know how it was designed a priori), and not having enough prior expertise such that your ramp-up time would be low enough to be negligible, should you ever need to touch that thing at some point. You need to realize, these folks have done so much work that they even get rusty on their own research topics after a few years. That doesn't mean they stop being experts on their topics. On top of that, they still keep up with their colleagues' research in other related areas... which, mind you, are likely to be more advanced than what you're doing. Chances are if they spent a day or two reviewing other stuff, they'd be as good (or even better) experts on them than they were originally, quite likely better than you (again, generic "you" here, as above).