Comment by Gigachad
6 hours ago
A proprietary format would allow doing anything, without having to worry about how other programs will support it.
There’s a conflict between what is needed to simply display images, and what is needed for an ideal editable document.
A web browser doesn’t need the complexity of non destructive Boolean operations, but an editor program does. It can all be exported to SVG at the end once it doesn’t need to be edited anymore. Things like variable thickness outlines can just be turned in to filled Bézier curve shapes that happen to be the shape of the outline.
You don't have to have a proprietary format to do that.
You are doing the mistake of associating open format with standard format, which really are orthogonal concepts. Open format means the format specification is published under an open license. A standard format is one whose specification is maintained by a standards organization/body/consortium. It happens that most open formats are or end up being maintained by a standard body out of convenience[1] and because people often publish them in the open with the hope it will also be used by others but it doesn't have to be. You as developer of application foo can publish the spec of your .bar format on foo's website under an open license and do the fuck you want with it while not being limited by the potential slowness of a standard governing body.
[1] mostly to avoid multiple incompatible forked versions of the format being used with the same name and confusing others.