A small point of order
"Prior groundings such as the Comet I (c. 1952), Lockheed Electra (c. 1959), the DC-10 (1979) and 787 were based on physical evidence of a potentially catastrophic problem with the aircraft. In this case, such physical evidence is, to date, completely lacking."
The L-188 Electra fleet was never grounded. Restrictions on max IAS were imposed until the flutter problem was worked out, but unlike the DC-10s and Comets, they continued to operate. That was a decision based on the economics of an airline whose sole equipment was the L-188, and also because no-one knew how the two mid-air breakups they suffered had related causes.