You are right, but actually I think you would want to go beyond that and build a hybrid of your approach and their approach:

For your documents, you will usually want your approach. Maybe with some optinal allowance for useful things like a "recently used documents" menu or something.

But for more enviromental things, I would want at least the option of allowing all instances the same access without a lot of permission prompts later on. E.g. my git config, my fonts folder, my code snippets library, stuff like that.