That's true, but doesn't really negate the principle... the set of layers is just different. If you're heading to that high elevation where it's mostly cold, you probably don't need to bring shorts on the off chance it's 85F one afternoon - you just wear your lightest pants that day.

The other things I've found is it's pretty darn easy to wash a few items in the sink while traveling. A 14 day trips doesn't require 14 pairs of socks - 4-5 is plenty, just wash them. Etc. Most people massively overpack. I'm always amazed at the number of people lugging around full size rollers at the train station.