The FAA definitely bears some responsibility, but not because the regulation is too stringent, it’s because they looked the other way. Recertification is onerous for a reason; it’s safety we’re talking about, and the result of not being careful enough is exactly what happened, hundreds of deaths. The FAA’s process in this case is already a product of regulatory capture; Boeing is already practically certifying themselves. Lots of reporting on this already; it’s easy to find more info.