As kids, we were given the opportunity to play with different materials and arrange our own world. We could cut paper in pieces, color it with markers, glue it, create forms from plasticine. Everything was a mess, but midst the biggest chaos we knew exactly what we were doing. This is strange considering that today we have so much order in the way we design websites, that we have started to just think only about the next component we'll put on the page, simply because it needs to follow that order. This linear thinking is predefining an inflexible path, so that when we are stuck, we often can't find how to quickly get out of this unfavorable situation. All that matters is just the next right detail or asset to create and not just to create anything. Then young designers get accused of thinking too much, when the opinion is that they should be creating anything.
Collages are practically arrangements of carefully positioned elements that divide the paper media in interesting, expressive ways. Composition is something we have on the web too, but right now it's not collage-like. We have tables, box model, floats, grids, regions, flex boxes and others, whose role is essentially to increase the order in the already ordered. There isn't a CSS chaos API or something that quickly allows to throw things on screen, see how they look and move/manipulate them around in an more intuitive way than changing X-Y values of the element's coordinates. People who have worked with CAD software probably know what I mean. The value change is the consequence of the action, but we still think of the first as the cause for the second. We need to be able to mold what we already see on the screen. Otherwise we'll always be forced to switch between different editors for code, images, audio, video, etc. Users on mobile devices require more immediacy in interactions, but it's hard for designers to give something that they don't have. Applying the position property to every element on screen, especially when there are many, probably wouldn't be very pleasurable. I'm not saying to create chaos, but to have an easier way to introduce a healthy dose of chaos, because too much order can often lead to a boring composition. We can create the right type of order only after we have found out why the chaos doesn't work.