I think the author implies that the hypothetical $4 service adds no value, other than changing the pricing and ownership terms. Imagine if all doorbell manufacturers decided to only sell a subscription service and not a device to own - then from a one time $50 purchase, they've milked you into $4/month for life. The camera and security will be a $4 extra, per month. Premium AI with real time face recognition (from Facebook of course) will be another $4 extra.