I agree we're talking past each other somewhat, but it really feels to me like you're missing the point. Here's the convo:

mg: This is a great example of how useful the File System Access API is ...

auggierose: the API is not supported (yet?) either by Safari or Firefox

you: describes the current situation with cross-browser file input support, says it's a "developer education problem"

me: this specific use case really does need the full API

It read to me, and still does read to me, like you were saying that Kinlan's use of FSA was hubris.