Yes, things do have costs, and they must be paid somehow, either directly or through things like advertising, which comes with its own set of rather perverse incentives.

That most people value convenience and no direct cost to them is just a fact of the world, and I genuinely don't see the harm in companies providing services that fill that desire. There certainly are other things that they do that absolutely can be criticized, but "providing a free service that people want to use" isn't inherently objectionable.