[filmgirlcw]

Ok, but imagine you’re in a situation where you don’t have the ability to install apps, or you’re temporarily on a platform you’re unfamiliar with and so you don’t know what GUI tools exist. This is why people wind up using web-based converters, which as another commenter noted, can be hijacked for malware.

A WASM solution might not be the most performant but it will be an option.

As for the web not being a good application platform, that ship sailed 20+ years ago and at this point, it’s hard to find any “native” apps that don’t share at least some similarities or core components as web apps, even if it’s just for UI. Although I personally would rather have a good native Mac app than a mediocre web app, I’d rather have a well-written web app than a mediocre Mac Catalyst app, and in many cases, than running an iOS app on the Mac. And I often prefer a web app or app built with web technologies to “native” apps built with GTK or Qt.