I'm trying to outline a useful definition of "[bad-]monopoly" that captures the stuff we generally care about when we worry about them.
It's important to have a definition that excludes "they're just unusually good and so people happen to be currently buying from them, purely as an issue of merit". (If Joe happens to be the best hot dog vendor on some intersection, that's different than if he can prevent others who want to from opening shop nearby.)
I said Google doesn't count as the kind of bad-monopoly because they're easy to switch away from, and the market share isn't self-reinforcing.
It doesn't follow that Google is easy to take market share from. That could be the case of "legitimately good at what they do", and is not how you should define a worrisome monopoly.
A company being so good that others can't gain market share isn't (necessarily) a bad-monopoly. Only if that difficulty came from the factors above, would it count as a bad-monopoly.
(Those factors being the vendor lock-in and the self-reinforcing aspect.)