From Stan reference,
The default is to randomly generate initial values between -2 and 2 on the unconstrained support
It seems to me that it makes more sense to randomly generate initial values from the prior. A priori, I'm saying that I believe that these values make the most sense. Starting an MCMC chain from somewhere that has a possibly minuscule a priori probability doesn't intuitively make sense to me.
What is the reason for Stan's default?