You have to get there from the start; the app store has to be there from day one. Since that didn't happen on the desktop, it's pretty hard to retroactively introduce one (although Microsoft is trying hard).
Thats being pretty pedantic. Introduce one successfully is a pretty obvious implication. Even after almost a decade of desktop app stores they’re still really struggling to get user acceptance outside a few niches. In fact the only one I’d count as an actual commercial success is Steam.
