So, again, why is this distinctive from the natural monopoly that Microsoft attained and illegally abused to restrict competitors from having equal access to their platform?

I believe Apple has been forced to make some concessions.

In any case, their chunk of the market never came close to Microsoft's. Also, Microsoft aggressively went after the domains of other companies, like trying to take over the Web (with some success). Apple is protecting their own market.

You do have to be careful about cooking the goose that lays the golden eggs, though. I don't feel like people are actually "playing the tape through," and thinking about the long-term ramifications of these policies.