According to Adam Smith himself, competition only works in well-defined markets. Creating a phone, as it stands today require being a hardware vendor yourself, or ordering in such high quantities that hardware vendors would actually care about you, while simultaneously you are a huge software vendor who simultaneously managed to capture enough users to make it worthwhile for third-parties to target the platform.

Remember, not even Microsoft managed to pull it off and not for lack of money or try. There is simply an inherent local minima/maxima for these 2 platforms.

How do we expect a third competitor to show up? It’s like expecting a 4 years old girl to compete with heavy-weight MMA champions. The rules around a market are the only reason capitalism could work, otherwise we would only have paper-clip machines sacrificing everything for profit.