Well, I think intrinsic ineffeciency of storing all that data inside your central and then running huge spark jobs to crunch through them creates huge costs in the first place that probably needs to be offset by higher margins being charged from the end consumer. If you can just monitor the users engagement with your offering and charge on that without having to actually go through countless logs to do that, might be what the author is leaning to. But yeah, easier said than done. Knowing which metrics to capture back centrally itself could be a challenging thing to do, if the data is decentralized ....