They are powerful from a computational perspective, but the point was that it's a hassle to run a custom binary on them as compared to regular computers. You get a powerful device that is not flexible in this specific sense, so much of that power is not utilized
You are not allowed to run computations that have not been approved by Apple if you are using an iPhone. Yes, the hardware is powerful, but it is cryptographically locked down. It is physically local, but the control of the hardware is entirely non-local and 100% owned by Apple.
Case in point.
> Apple has locked my Apple ID, and I have no recourse. A plea for help* https://news.ycombinator.com/item?id=46252114
> Apple bans entire dev account, no reason given https://news.ycombinator.com/item?id=44601548
I could have a stroke that leaves me unable to program. Does that mean I am not truly free to program today?
Those are risks, but they do not change the on-the-ground reality today, and the claim was that users, today, cannot use these device as general purpose computers.
In my Linux and Mac, I dont think twice to quickly write a script to automate some pain-in-the-butt issues. But with my phone, it is pain-in-the-butt to write anything. It becomes not worth the effort.
Moreover, we can argue if technically it is a general purpose computer for whole day long. But that's not the point.
The point is that we are allowing gradually the big organizations to restrict general purpose computing, the internet and other previously free systems. It is happening slowly, where we can still give them the benefit of doubt. We are the frogs in the kettle where we are arguing that the temperature is just one degree more than earlier, so it is not actually boiling. We can keep on arguing about the temperature or step back and see the big picture where it is going.
This is not a rhetorical sleight of hand, this is just saying that I am not truly in control of the device that I have bought.