Some of us were around for the last set of changes: * https://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005#Change_to_daylight_saving_time https://en.wikiped

Some of us were around for the last set of changes: * https://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005#Change_to_daylight_saving_time https://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005#Chan... * https://en.wikipedia.org/wiki/Daylight_saving_time_in_the_United_States#2005%E2%80%932009:_Second_extension https://en.wikipedia.org/wiki/Daylight_saving_time_in_the_Un... Much patching / updating of tzdata and rebooting. I think that effort led to a bunch of changes that make for easier updates going forward. Until that point there wasn't really that much churn in things over the past few decades, so people became a little more bit complacent when it came to TZ code.