[rudi-c]

It would be quite challenging to make such a business model work with collaboration-centric features. Features such as multiplayer editing, in addition to requiring some carefully designed technology, require the two clients to be running the same version of the code. As soon as you introduce a new feature -- e.g. a new type of object that you can insert into the document, you need all clients connected to the same file to be able to understand that object.

This is just one of many types of edge cases that can crop up. It's kind of like database migrations except a lot of work happens client-side too.

You could put the onus on the user to deal with making sure everyone you're sharing a file with has the same version (or whatever asset is involved in a particular tool, this is not design-tool specific). But the friction to sharing raises considerably. Even if your whole team is on the same version, what happens if you try to share a file with an external client, etc. You'll be making tons of tradeoffs in engineering time and feature design to deal with the fact that users don't get the latest version of your app just by loading the page. Your tool, though it might still be excellent in other regards, probably won't end up having collaboration as a central selling point.