That's a complete oversimplification. There was a whole "AI winter" in the late 20th century, during which there was very little progress and/or funding.

Also, for all we know, neural networks can just plateau. We'll take it as far as we can, but who knows what that is. Saying "if you squint and tilt your head it tastes like exponential" inspires only like, 60% confidence in me.