While I agree with the idea and I am not happy about slow apps, the truth is, it's focused on technical details.
People don't care about speed or beauty or anything else than the application helping them achieve their goals. If they can do more with current tech than they could with tech 10-20 years ago, they're happy.
Every statically backed research on customer behaviour I have ever seen says otherwise. The more you slow down the page or app the less customers like and use it or buy the product being sold. As someone with a homemade site for our business I can say that it is extremely easy to be faster than 95% of sites out there and it makes a huge difference, also on Google. Tiny business with homemade website in top 1-3 on Google was mindbaffling easy because everyone use too many external sources and preschool level code. Especially the so-called experts. Most are experts in bloat.
People don't care about speed or beauty or anything else than the application helping them achieve their goals. If they can do more with current tech than they could with tech 10-20 years ago, they're happy.