Of the over 100 historical ash encounters only 8 involved immediate engine malfunctions. Just 8%! and that involved some pretty heavy ash.
Statistically there are not going to be that many aircraft "dropping like flies".
On the other hand there seems to be some evidence that hot section deterioration can be the result of "invisible" dust. Therein lies the proverbial rub. The implication is that there might be some compromised turbines that could fail catastrophically at a later date,100 hrs, 500 hrs, who knows?