In F1 the 'shearing' effect of the CF components is too rid the "cage" of protrusions that can cause the safety cage to roll/pinwheel/stop dead by sticking to something like a wall/another car or digging into the ground, as well to prevent skewering another driver. The nasty splinters , are ...well, nasty splinters, with all the evilness associated with high speed sharp things. Definitely worse than running with scissors.