Hard to say from looking at the results of a single crash whether the frame was weak or not. Crash forces are rather chaotic and seemingly similar crashes can have drastically different effects depending on exactly where and in what direction the peak forces occur.

The only crash I've had that damaged one of my bike frames was a T-bone type collision with a medium-sized dog (black lab) on a steel bike (531 DB). Both the top and down tubes buckled although no other components were damaged and the wheels remained true. It didn't come apart like the OP's frame, but it wasn't salvageable either.