The Mac App Store is not a failure from the user side, it's where users would look first. Nobody wants to have to go to different websites/repositories every N days to update all of their apps/drivers, or put up with spam from 10 different update notification mechanisms. I still remember that hell from barely 12 years ago. Why do you think gamers flocked to Steam?

As a developer, it's more of a failure of Apple's dismal documentation; I -want- my product to be a nicely sandboxed, well-behaved citizen that only accesses exactly just what it needs, but the state of macOS API documentation was too grim to learn how to do that the last time I tried (like "security bookmarks" and "file providers" from a relatively-simple Swift app).