The thing is, there's a big gap between "mass-market software that can budget for the friction of an app-store release" and "niche software that only advanced,

The thing is, there's a big gap between "mass-market software that can budget for the friction of an app-store release" and "niche software that only advanced, technical users know or care about". It's perfectly possible to have niche software that only, say, accountants care about; or niche software that only bee-keepers care about. It would be really nice (in the "this is why we can't have nice things" sense) if there were a way to distribute software tools to niche audiences without them necessarily needing to be technical audiences. Up until recently, the Open Web has been that system, but it seems Google can unilaterally disable it via their Safe Browsing feature.