My dad uses this program. It sounds insane to me, but when I expressed some distaste for the idea, he pushed back and said he loved it. I have a hard time understanding that point of view.
I guess, this program can be viewed by your dad as a "being able to print - as a service" offering where the value is not only in being able to print, but also in being able to stop caring about ink cartridges. Some folks don't mind to pay for services that take trivialities off their minds.
I can't get behind these things and I carry some animosity for people who support and spread them. In both cases, I think the people supporting/using these things are not thinking things through and are only thinking about today at the expense of tomorrow. I think this is the core of my struggle when I try to understand the other side.
On the one hand, thinking about ordering ink is a thing of the past (a fairly trivial task for a home user imo). On the other hand, when the internet goes down, or something happens which impact the user's ability to pay a monthly fee for ink, their ability to print is completely gone. Never mind that they have everything they need and have paid a lot of money over time for it. The printer then becomes e-waste, even when it should work perfectly fine under a different pricing or subscription model. A simple ink monitor with an auto-reorder based on usage patterns should be enough. That wouldn't require locking it down, the user could cancel any time and still use the printer/ink they have... then if/when they are ready to sign back up, they can. Or just order ink ad-hoc. I'd have no problem with this.