Mobile phones were severely constrained by hardware that made them impractically expensive and unwieldy, and also by the time it took to set up wireless networks at a large enough scale. That's why it took mobile phones a few decades to really get going, and this is going to be different for every other technology.
LLMs, for instance, were not as hardware-constrained - we have a lot more compute now, but there wasn't a hardware paradigm shift or anything, things were already pretty good a few years ago - now it's just about scale. LLMs were also always relatively affordable - there wasn't a period where they cost $10/token, so we don't get the same kind of affordability scaling as with phones. They also utilize existing internet infrastructure and don't need to be rolled out in some new worldwide grid.