True enough... It's just that boiling takes a fair bit of time and fuel. It also makes water taste flat and otherwise unpalatable IMHO at least until cooled down, which generally takes too darn long. OK in a cold climate but less so in summer.

This is why I often find chlorine tabs more convenient. Even filters are a good option on the move. Boiling is a reliable old-school method but only workable IME at a campsite or overnight shelter when you have plenty of time to spend at a fixed location.