Though surely you'd agree that just because some predicted consequence of an effect at one order of magnitude fails to occur (or occurs at an acceptable level), doesn't mean said effect is therefore irrelevant at any scale. The advent of radio led to a number of predictions about negative social consequences. Similar concerns were expressed over television, and then again over social media. We could debate whatever negative consequences radio and TV had, but the exceptionally negative consequence of social media are indisputable at this point.

So too here, one could argue the positive/negative impacts of things like the calculator on our mental capabilities, but chatbots are taking this automation of mental processes up an order of a magnitude both in terms of the breadth of things that can be "input", and the variable quality of what is output.

The unfortunate thing is really the only way to test this is to basically do what we did with social media - just let a generation have at it, and see what happens.