> How on earth is this possible?

I'd put some huge blame on single page applications. Nearly everywhere stuff gets replaced by SPAs to push all layout calculations to the client. This frees up resources on the server side but at the same time everything feels sluggish and takes a long time to load (network- and Javascript-wise).

Reddit is also taking this new approach and as a result is nearly unusable on my phone and takes 3 times a long to load on my desktop.

The layout is becoming mobile first due to everything needing to be "responsive". So the desktop as the minority webbrowsing platform gets to use all the interfaces that are primarily optimized for mobile.