That's the very reason I've been buying from "someone else" for almost a decade. Still, in certain markets they are not a "minor" player, and even then that still doesn't give them an excuse to abuse the position. Yes, they are a minor player compared to the WHOLE market, but if you compare only the segments they actually put the effor to compete in, they have quite a large slice and they rake in more profit than anyone else from it. You can't reasonably use under-$200 phones to justify the fact Apple doesn't have a monopoly when they refuse to enter that segment. You may even argue that if that's a valid argument they would never want to sell cheap phones in the first place, and that market share isn't a good metric for anything.
I don't see why the option to sideload stuff onto the iPhone you've bought would make the platform less secure, especially if it is disabled by default and requires explicit user consent to be turned on.
Also, their focus on "security" has always felt very phony to me, as much as their focus on "standards" always basically meant they only evangelized for interoperability when it suited their interests. What they have been doing with iMessage in the USA is the epitome of abusing your market position, but I guess the FTC doesn't really care about that.
