Re: Why strip strike?
After 30+ years of fly fishing I used the strip strike for the first time while striper fishing. If nothing else I really enjoyed the exhilaration of the immediate connection to the fish. Where as with a lift of the rod I do not get that. I also found reaction time was much quicker, because when swinging streamers I felt the bite. I didn't address the machanical reasons for it, because others have already. I will say this I found it quite easy to strip strike several times if I didn't feel confident in the initial strip strike and have never been able to do so with a lift.
In situations where a lift is the right action I don't strike you see the guys do in bass tournaments I just deliberately lift the rod in a smoth motion.
When Tight Line/"Czech" nymphing I do a short quick down stream wrist snap.
Attention New Fly Fishers and those just wanting to improve- Join a Fly Fishing Club. They have classes on every aspect of fly fishing for beginners to advanced for free or cheaper than offered elsewhere. Some offer mentor programs. You will make friends with other fly fishers. Clubs often have outings in which members pay special group rates for guides or to fish prime private access areas.