The next person to work on the frontend paging code will likely look at the existing code and infer the contract from there. Doesn't matter how healthy your inteream communication is, humans just straight up don't work like that.
The documentation already says you have to use the nextToken from the current request - adding more words to the effect of "no, really, you do *have* to use the nextToken from the current request" is sadly unlikely to help in practice.
It isn't about making things more opaque for one's own team, it's about stopping people *accidentally* doing something unsupported, which is if anything a kindness to your colleagues since they won't end up with an apparently working feature that will break unexpectedly later.
OP is aiming minimise unpredicted future pain for his team, his colleagues in the front-end team, and their users.
Your point of view would be absolutely correct in a world where "everybody would just" ... but humans, as a species, don't "just" - so code accordingly.