Sad thing is that most of the web sucks on rather fast connections too. Pages being almost 5mb of data, making multiple dozens of requests for librairies and ads. Ads updating in the background, consuming evermore data.
I don't notice it much on my PC, since I've got a FTTH connection, but on LTE and 3G, it's very noticeable. Enough that I avoid certain websites. And that's nowhere near slow by his standards.
I do agree that everyone would benefit from slimmer websites.
I have Javascript off-by-default, and about 80% of the time it simply makes everything better.
Oh, sure, a few sites need JS (and get whitelisted) and some just have minor layout quirks... But I can actually scroll down and read the text of a news article rather than suffering through waiting times and input-latency as Javascript churns.
I also use an add-on called Decentraleyes. It caches various common scripts from popular CDNs within the add-on itself so your device doesn't need to make any network requests for them. It was originally meant as a privacy to but the caching seems to be at least as valuable.
Figure out a few interesting/useful websites that work fine without Javascript. Try browsing those for half an hour, then switch Javascript back on and browse your usual websites. You'll probably notice it's so much slower, even with FTTH, because of network load but also CPU (and marginally RAM, though modern browsers are mostly to blame for that).
I don't notice it much on my PC, since I've got a FTTH connection, but on LTE and 3G, it's very noticeable. Enough that I avoid certain websites. And that's nowhere near slow by his standards.
I do agree that everyone would benefit from slimmer websites.