So what should I do if I want to make an app with this functionality? Do I have to tell users to download and run some executable? You can imagine a case where that is a bit riskier than a nicely sandboxed web app with permission to access one directory.
> Do I have to tell users to download and run some executable?
Well, yes.
The alternative is to give any malicious ad the ability to drive-by-download malware onto your machine.