Earlier quoted context omitted.
I find that extremely unlikely, only because companies aren't entirely stupid, and if MANY companies have started doing that in this space, and since they started it their profits have gone up significantly, it points to this kind of tracking making a significant amount of money. And most of the tracking happens on the server, the client really only keeping some tokens for state and sending them with the requests.
> only because companies aren't entirely stupid [citation needed] Cents per user is still a lot of money if you have a billion users. Maybe the real value of tracking is the perceived value of tracking? It's a good way to combat competition as tracking requires that you already have a large presence.
Now companies might do dumb stuff, but they don't just continue to grow and dominate by making exclusively bad decisions. Google is built on targeted advertising, and it's paid off for them very well, so it can't be a complete boondoggle.
The wikipedia article on targeted advertising says that targeted ads make about 2.7 more money than the alternative.
I don't have any numbers on material costs, but I can't imagine it costing users that much in electricity. Still, it is just a guess so if you have anything that shows otherwise I'd love to read it!