Shuttle external tank foam problems

Did the EPA bring the Shuttle down? From NASA’s application to the EPA[*1] for a waiver from the CFC ban:

A reduction in compressive and tensile strengths was also realized due to the change from CFC 11 blown foam.””The new foams were also more susceptible to a phenomenon known as “popcorning”, sporadic loss of small pieces of foam at low heating rates, leading to ET Intertank foam loss that ultimately resulted in Orbiter TPS tile damage.