I wonder if there's something like the Doppler effect going on here. The field continues to advance at a constant rate, but it takes time for news to reach us, proportional to the distance between us and the frontier.

To a stationary observer, it would appear as if the time between developments is increasing, and that the field is slowing.

I hope I'm wrong to use this analogy, though. I'd like to continue thinking of myself as relatively informed about technology.