It has been proven that a Turning Machine and Lambda Calculus have the exact same equivalent expressiveness, that encompasses the _entire set_ of computable functions. Why are you so sure that "text prediction" is not equally expressive?
Was Hellen Keller not intelligent because she lacked the ability to see or hear? Is intelligence defined by a particular set of sense organs? A particular way of interacting with the environment? What about paraplegics, are they disqualified from being considered intelligent because they lack the same embodied experience as others?
Whenever you give someone kudos for being brilliant, it is always for their ability to successfully compute something. If that isn't what we're discussing when we're talking about intelligence, then what are we discussing?
On the other hand, you are clearly stating that intelligence is computation. But you're right, it would be too easy to ask you to define what any of those words mean AND to back that claim.
Given that, the constant drumbeat of pointing out how AI fails to be human, misses the mark. A lot of the same people who are making such assertions, haven't really thought about how they would quickly accept alien intelligence as legitimate and full-fledged... even though it too lacks any humanity backing it.
And why are they so eager to discount the possibility of synthetic life, and its intelligence, as mere imitation? As a poor substitute for the "real thing"? When faced with their easy acceptance of alien intelligence, it suggests that there is in fact a psychological reason at the base of this position, rather than pure rational dismissal. A desire to leave the purely logical and mechanical, and imbue our humanity with an essential spirit or soul, that maybe an alien could have, but never a machine. Ultimately, it is a religious objection, not a scientific one.