[beernutz]

This is just not true. you did not have to specify fixed width in flash any more than you do with HTML. Flash's approach used something like a constraint solver to allow some areas to grow and some areas to have anchor points. It was reactive by design.

[tabtab]

I think the key is that what the browser (client) gets should be coordinates. If the server side wants to use some wazoo auto-layout engine, that's fine. And that gives one a wide choice of layout engines/algorithms, unlike browsers.

Yes, browsers do have different layout engines available, but they all go through buggy and inconsistent JavaScript and CSS in the end: the chain is as strong as the weakest link.