Was IE dominant in the browser space in 2007? It feels like Chrome or Firefox had surpassed them by then. Microsoft still got hit because it was the Most Favored Browser on the most dominant OS platform.

Again, having a monopoly isn't illegal. Abusing a monopoly to force unfair competition in a new market is illegal. Apple isn't taking the hit because they're dominant in ebooks, but because they're not playing fair with ebooks when it comes to the mobile device market where they are a strong player.