[prmoustache]

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.

[jasaldivara]

I don't think they are saying "proprietary" as in "secret, closed source", but just as in "custom format" that is built around one particular application.

[ltlnx]

The problem with SVG is the different demands between browser vendors and graphic editors. Browsers for example don't need pages to be in SVG, but it's unavoidable for proper graphic design tools. That makes the advancement of an open format a lot harder, and AFAIK Inkscape devs have thought of extending SVG into their own format (in a talk at LGM).