I agree that, for the end-user, a low-level format like PostScript is perfect. No need to preserve structure. But tools like Illustrator need to preserve some

I agree that, for the end-user, a low-level format like PostScript is perfect. No need to preserve structure. But tools like Illustrator need to preserve some structure. Otherwise it becomes very difficult to make edits. (Imagine reflowing text in a PostScript file – next to impossible!) Even Photoshop preserves lots of structure these days, so you can perform non-destructive edits. SVG's other use case is interactive animations. You could equally use Canvas for this, but it's nice to be able to import resources directly from e.g. Inkscape, and manipulate them using the DOM. Easier to build an animation authoring tool around structured SVG than unstructured PostScript or Canvas.