If Linux was 90%+ of the market, getting people to download some stuff with a curl command promising some BS or having people download and run sudo would only need to touch a fraction of users to be highly valuable. That's just a random example off the top of my head. And also because I don't use Linux on desktop so I don't fully know how everything works there.
And if someone thinks regular people would be "too scared" of CLI to pipe curl into sudo sh, remember that people are "too scared" of developer tools in browsers too, and yet Facebook and others have to implement self-XSS protection measures in there, because it turns out there's nothing too complicated in computing when it stands between a person and fulfilling their desire (as promised by a scammer).
I'm sure that's not true for all Linux repositories. But humans certainly do look at all apps going to the App Store.
So, this strategy would barely work, as users would only look on the internet for a download, if it's not in this trusted repository and then it's gonna be a really unpopular application. (Theoretically, it's possible for your grandma to go on the internet before checking this trusted repository, but that is really just so much more effort.)