This is the Parable of the broken window [0] in action. The piles of cash that the ad duopoly are sitting on could (and would) be spent elsewhere, and that would benefit us more (by my assertion above)

It's not "look at all the money they made, this service must be valuable", it's "is the money they made the best possible use of those resources?" and my answer is "definitely not"

[0] https://en.wikipedia.org/wiki/Parable_of_the_broken_window