Carbon hates side impacts and forces it wasn't designed for more than metal does.
Now, old steel racing frames were of course made from very thin-walled tubing, whether that be in the '70s and '80s, non-heat-treated and heat-treated examples. For those of you old enough (as I am not) who watched racing or did racing, when there were heavy crashes or ones with frame damage, where were the usual points of bending or failure? Perhaps a steel tube or tubes wouldn't snap, but would still fold up spectacularly. Serious question. Just would like an objective answer, if possible.
Yes, a snap failure is how carbon does it, and it's not a pretty sight, but neither is a metal failure. If anything, the snapping helps dissipate energy and momentum. We see this all the time in racing--Formula 1, WEC (think Le Mans), etc. A carbon tub/frame is built around a driver with various chassis and suspension and engine pieces bolted to it or around it. In a crash, everything explodes upon impact, but the carbon tub is generally fine (good!) and the failing other pieces take energy out of the car-flying-off-the-track scenario, to the benefit of the driver. We don't bat an eye at the lightweight construction and use of carbon in racing, yet see its immense benefits in crashes. I'm not saying metal of some sort wouldn't do a good job, it's just that carbon does quite well for itself in auto racing.
At any rate, the Tour this year has been exciting!