Wrong. Both were lost because of a fundamentally BAD ARCHITECTURE. And that architecture was bad because the NASA engineers who designed it, had never designed anything like it before and were never able to test or evaluate any of their assumptions.

Columbia would not have been lost if the Shuttle was top stacked, instead of side stacked.

Challenger would not have been lost if not for the use of solid rockets to launch humans.

Both of these design decisions were done to reduce development effort.