For example, cable TV (from whereever you are from), Netflix, HBO, Amazon Prime is 4 already.
For gaming, there is Steam, Origin, Battle.net, GOG that's 4 already.
If you take a smaller "app store" like Origin the question arises why does this even exist? It brings nothing on top of Steam.
If you want to compete with a product you need to compete on price or features. Well, price is zero, so you gotta compete on features. They can't compete on features, so EA enforces you to use Origin. Screw that. I want all my games in one managing app.
The reason Origin and Battle.net exist is because EA and Blizzard want control and keep people within their own infrastructure and offerings. I do get that from Blizzard's PoV. From EA's, not so much.
Plus that only works because they're reasonably big, and I doubt it works on the long term.
Valve, instead, choose to not only distribute their own games but also provide a complete platform for other publishers. They even allow you to import games which aren't on Steam such as Battle.net ones.
GOG specialises in DRM-free games which Steam doesn't.