If you take those people who are not good at transferring O2 with reduced pressure, ( they're old, have a cold, smokers etc) and then give them 5-10 seconds of severely reduced pressure while they don their masks, then expose them to 13 or 14,000ft for a few minutes, I think you may well have some people in need of attention ( medical O2 ) from the cabin crew.
Probably the only benefit one can ever get from smoking is
better tolerance to hipoxia / better survival rate with low O2.
Comparisons of altitude tolerance an... [Aviat Space Environ Med. 1997] - PubMed - NCBI