In the never-ending attempt to lighten parts, they are made more and more minimally to just about bear the loads inflicted upon them. More heft at stress points means more weight. All kinds of alloys are used for two reasons; one they are light and two, they are cheap. Bolts, brackets, wheels, etc. We keep chasing light weight and the manufacturers keep making items lighter. Any type of stress put on a part from a differing direction could break a part. I have seen broken bars, cranks, derailleurs, etc. A racing bike is like a finely tuned watch, pretty, useful and fragile.