Ahh, now that is an interesting angle, but that would suggest that the rate of introduction of new technologies is linear and that every new technology must have a period of exponential growth initially.
(Or I suppose... That the rate of introduction of technologies with initially exponential growth rates is linear. You could ignore those without exponential growth rate provide that a constant number did.)
I think basically at any one time there are a lot of competing new-born technologies, and it's only in retrospect that we can see which of them will go exponential through a feedback cycle of improvement and growing adoption.
It's not so much that technology always goes exponential. It's that in retrospect, we notice the ones that did.
(Or I suppose... That the rate of introduction of technologies with initially exponential growth rates is linear. You could ignore those without exponential growth rate provide that a constant number did.)