Of course, people say now, the situation with Google is very different. With Google, you have a choice. You can either use their products or not. But it’s not that simple when they offer superior products for free. You rely on them, because you often have to use one of their products, because Search, Maps or Gmail, to name a few, are all far more superior than what other competitors have to offer. And if there’s a new kid on the block they can’t compete with, they simply (try to) buy them to maintain their implicit monopoly position.
This is a very... interesting definition of monopoly and by interesting I mean "don't be surprised if people disagree with your conclusions when you are re-defining a crucial concept, monopoly, to fit your argumentation". Every single Google service has a ton of competition, even Search, and you can migrate to these anytime you want.
The fact that Facebook is used as a example of a non-monopoly because people aren't relying on it, is a humorous non sequitur and obviously false. Lots of companies rely on Facebook as the single largest social network through which they do most of their marketing and community outreach. Does that make Facebook a monopoly? Well...