Microsoft has always had a love/hate obsession with monopolization. In the early days, they were famous for stating that strategically they wanted to be the platform people-who-were-not-MS made software money on, because that was how you became a dominant platform.

But of course that buckled at various times (first with proto-Office vs 1-2-3 & WordPerfect, then with the 90s dominance / Encarta-era smorgasbord of random MS software).

Excel was released on Mac because Microsoft wasn't confident in directly challenging 1-2-3 (on DOS) or early-Windows capabilities. And ultimately, it was exactly the fact that Microsoft owned the OS that allowed them to dominate in office apps and browsers in the 90s/00s.

Apple has had a monopoly on two device platforms (iPods, then iOS) and has abused both of them to its own profit.

ATT didn't have a government mandated monopoly: it had a series of every-few-decades consent decrees in which it bargained with the US government to avoid being nationalized. See https://en.m.wikipedia.org/wiki/Kingsbury_Commitment

Apple has acquired a substantial amount of software and developers. They just tend to do so at the nascent product stage (vs Google and MS acquiring later). See https://en.m.wikipedia.org/wiki/List_of_mergers_and_acquisit...