Even then its still a headache.
Just because someone else fixed the library, doesn't mean my servers and embedded devices have the update yet.
Presumably by "the library" you mean "the tzdata files"; this involves no code changes. The whole point of the Olson timezone database and library was to remove any knowledge of specific daylight savings time rules from any code whatsoever, so that changes to the rules could be handled without having to change source code, recompile, and relink every program (this was back in 1987, when shared libraries were still somewhat rare on UN*X systems). Thank you, Clorox and company.
But there still needs to be an update, and that might require restarting processes that have already loaded the now-out-of-date rule information, so, yeah, it's not as if the timezone cabal can wave their hands and magically update all the systems out there.