I say it depends on the frame design.
I have snapped 2 alum frames at 230 pounds.
I have a Cannondale that is solid. Can't count the miles.
I had a Trek that was wimpy at the bottom bracket area, snap! 13,000 miles
I had a Lemond that was a sweet ride but had cutouts at the rear dropouts (to save weight I am guessing). I had never paid attention to that design till it snapped at the aluminum section. Believe it or not, also at 13,000 miles.
I ride carbon now as well as the alum Cannondale.
No problems at all with the full carbon.
If I ever get another alum frame, I will pay close attention to the weight saving cut out design and the flimsy BB area.