even an optimist should admit that this tendency leads to atypically slow and unreliable progress.
What does he mean by "atypically slow"? What's the typical rate of progress and how is it slowed down by this phenomenon? It seems that, whether real or not, this ossification is a part of what one would consider "typical".
I think what Bryan meant was that if it weren't for our tendency to conform, and to punish nonconformists, then progress would be faster. I agree.
Here is a new post at EconLog in which Bryan Caplan discusses how signalling contributes to the status quo bias.