There's a big difference between exclusive licensing and non-exclusive licensing. New drugs (like penicillin) tend to be exclusively licensed because of the costs involved in regulatory approval, and that can slow down technology diffusion - the wrong licensee can sink the technology.

But enabling technologies (like CRSPR) get licensed non-exclusively, particularly when the patent holder is an academic institution. If the patents around CRSPR are licensed non-exclusively, at reasonably prices, and with appropriate treatment for academic researchers, these patents aren't going to slow science down.

A good example is the original polymerase chain reaction patents, which were held by Cetus. Despite lots of legal arguments, PCR was always widely available.

Here's a nice analysis of the PCR patent situation and its effects on technology diffusion: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1523369/