Why not add:
No wingsuit jumps? Not an expert.
No sitflying? Not an expert.
No pond swooping? Not an expert.
No CRW jumps? Not an expert.
All of those things are optional individual choices. The ability to stay safe in the sport requires water training, accuracy landing capabilities, and knowledge of BSR's and FARs. So those are mandatory to be called an "expert". They are fundamental things to know, regardless of what other specialties you participate in.
As an engineer, you're probably considered an "expert" in only some fields of engineering, but not all of them. You might be knowledgeable about structural engineering, but not know anything about fluid dynamics. You could be an aeronautical engineer and know nothing about electrical engineering. You don't have to know everything about all specialties to be an expert. But you should be highly knowledgeable about a few things.