Consumers have a viable and realistic alternative in Android and 80% of consumers choose to use that alternative. Consumers did not have a viable and realistic alternative to Windows in the 2000s.
My point is that Apple and Microsoft are different situations. You can't look at just the market share and ignore the other dimensions where they are arguable behaving worse than Microsoft ever did.
The illegality of what Microsoft did with Internet Explorer was contingent on them holding a monopoly on personal computing. They were using their monopoly as leverage to obtain other advantages. Apple does not have a monopoly on smartphones. Looking at marketshare is essential.