If New-York shifts its timezone, then it will still be New-York and America. And the new tzdata will reflect that shift so your data will always be correct (as in reflecting the time it is in new york). For local time, you will switch to a new city and the date will still be correct.

Exactly, but that is my point: usually my data is not intended to reflect the time it is in New York. Being tied to a (semi-)arbitrary city changes the actual meaning of the zone slightly. If every city was represented and I could choose "Boston" then that would make sense (for data is intended to reflect the time it is in Boston) but of course that's not entirely practical.

(I'll note that I agree with the general wisdom to store data in UTC; here when I talk about zones I'm either talking about user local machine time or display)