If it’s web native, anyone can just use it. If it’s a capsule, they first need to download the capsule app to associate the file extension with the OS and have it launch, right?

That feels like a big barrier, almost like a Java runtime.

In defense of capsule, the Filesystem API is janky and has kind of shit UX. Less sophisticated users would probably prefer the UX of a purpose built tool.

I prefer worse UX for the sake of standards and zero install, but many people would prefer the opposite. I don't think Capsule is intended for the HN crowd.