Web pages load much quicker, Firefox uses less resources, my browsing is significantly more secure (see [1] for risk of loading arbitrary fonts), and I can browse the web without Google/Facebook/AdvertizingCorp (and thus the Five Eyes) building a profile of everything I do. It's a nice feeling.
This set up also blocks ads served from third parties, which I feel is an agreeable compromise on web advertising. If I send a request to your website, and you send me a document with embedded images stored on your website, I'll download them and view them alongside the page. However, if you try to tell me "go send 5 unsecure requests to each of these three companies you've never heard of, and execute their 20KB of code, to get flashing ads alongside this page" - I'll ignore you.
Sites loading resources from external domains (usually Google) is nothing new. I've been browsing this way for two years now, and I've developed a healthy level of contempt for 95% of web developers. The vast majority of them just don't care for their users; campaigning to get the developers to change their habits is a broken model. Ultimately, you have to take control, and decide for yourself what you want to run on your computer.
I don't know why more people don't browse this way; some actually ridicule this approach ("get with the times"). It boggles the mind.
[1]: https://hackademix.net/2010/03/24/why-noscript-blocks-web-fo...