On modern phones, 99% of interactivity for 99% or users comes via the App Store. Many websites will actively ducktype and send phones to an App Store, which just becomes a broken link on your laptop-with-LTE. Hell, nowadays, some sites will cripple interactions via phone browsers to encourage app use.

If you’re downloading 200 mb pages every time because you’re loading desktop pages on your phone, it’ll be pretty slow and inefficient.