I think he's annoyed that lots of people are trying to re-implement the wheel using a poor AJAX based solution when an older solution is better, but no one likes using anything "old".
And all code is a moving target - nothing is future proof, especially where javascript is involved, but AJAX seems a lot more future proof than hacking image tags to do something other than loading images. It's baked into front-end templates and the caching strategies of the biggest sites on the web so it's not likely to go anywhere anytime soon.