I think this is one area where legal theory is not up to date with how society interacts with technology. For example, I strongly believe that Internet should

I think this is one area where legal theory is not up to date with how society interacts with technology. For example, I strongly believe that Internet should be considered something akin to a utility, because it's such an integral part of our lives. If an ISP were allowed to filter the internet however it pleased, it could have a substantial impact on our personal freedom. Same goes for smartphones. Given that there's only two realistic choices, the Apple/Google duopoly means there are real restrictions on what kinds of apps/services you're allowed to access. Yes Google allows you to sideload apps, but if you use the same arguments about "they built the platform, they can charge/restrict whatever they want" that people use for Apple, what happens if Google takes that away and you're left with no real choice? I would have a hard time defining a legal principle of which industries are so critical that they deserve regulation, but I would say there's definitely an argument for applying it to smartphones, and less for something like game consoles. Ultimately it comes down to political discussions to decide what is worthy of regulation; over time, we've decided that things like transportation, finance, communications, food, medicine, and so forth require regulation, while other areas are very loosely regulated if at all.