With today’s hardware I might have a different take - the 18 has more than enough hardware to be a laptop so maybe I’d use it for a docking mode. But my gut is I’d probably still want a laptop even then.
To me the upshot is : billions of development, software and hardware, have gone into the platforms - it’s hard to quickly make them significantly better.
iOS has come a long way since those days so a lot of the most common use cases of the past are no longer necessary. But the principle is the same - the hardware is a general-purpose computer but the software is locked down unnecessarily in many ways. Jailbreaking lets you do things that are outside of Apple's box.
The downside to jailbreaking was often the instability but that was also back when the phones were way less powerful. Today, armed with LLMs, I would love to have root on my iPhone again. I'd love to rip out Siri and replace it with Claude Code or something like that.