I think you are not considering the many websites for which this inefficiency doesn't matter. Sure, if you're write Google's main web page, every extra byte counts. But there are not many web sites where this is even close to be true.
For example, there is no big difference in functionality if the Adobe web site takes a few extra milliseconds to load. Customers just want to buy a product and get out of the way. And Adobe is a big company... This is even more true for their customers, thousands of small websites that just want to publish content as quickly as possible.
We aren't talking milliseconds, we are talking seconds to 10s of seconds. At that point, you are risking bounces, which any business-oriented site should fear, even Uncle Bob's Burger Bar.
For example, there is no big difference in functionality if the Adobe web site takes a few extra milliseconds to load. Customers just want to buy a product and get out of the way. And Adobe is a big company... This is even more true for their customers, thousands of small websites that just want to publish content as quickly as possible.