Ok, my image has 100% width for screens up to 800 px width, what height value do I have to set? You simply don't know this information at the time when the DOM is built.
The idea to set fixed dimensions feels like it comes from a time where we did designs with tables and "optimized" sites for 1024 x 768 pixel screen size.
That was the time when you could tell that this image should be displayed 200 x 200 px in size and nothing else. And it fit. One way or another.
Make no mistake, this is a silly problem to need to hack a solution for. So I would welcome lazy loaded images with space allocation before it's rendered with a responsive sizing.
The idea to set fixed dimensions feels like it comes from a time where we did designs with tables and "optimized" sites for 1024 x 768 pixel screen size.
That was the time when you could tell that this image should be displayed 200 x 200 px in size and nothing else. And it fit. One way or another.