Solution: block HTTP ads.

Solution to what? Publishers still have to enable HTTPS on their sites and they'll only do that once all the resources on the page are HTTPS compatible.

To this: http://idlewords.com/talks/website_obesity.htm

While I agree with the gist of that article/presentation, it's more on the silly side compared to many other more detailed and accurate pieces about the growing weight of the modern web.

While blocking ads will help some (and certainly some ad providers have gone way too far with their bandwidth/cpu requirements), the web is just a richer media experience than before. The mainstream does not just want text and 80-90% of the page weight ends up being images, even on that article itself. There are other advancements like HTTP/2 and modern CDNs and better image formats like FLIF that will solve this problem much more effectively without going back to a textual world.

Still don't see what any of this has to do with HTTPS encryption everywhere though...

Well, even Amazon (affiliate) ads server their image over http. So for whatever reason, even the owner of AWS can't serve their ads over https.

Do you need to use their widgets in the first place is another question.

The reasons are as described - a big company with outdated or poor tech policies. Just because AWS is advanced doesn't mean every use of it is. Clearly Cloudfront supports HTTPS and has for a long time so they can enable it if they want to.