This is in dispute. Yes, falling on your hand at the end of a locked straight arm would be very likely to lead to clavicle damage as well as other problems. But many believe that the ability of the elbow hinge in the arm to absorb shock by flexing and decelerating the fall more gradually actually protects the collar bone. This would be much like "slapping" the mat with your open palm when being thrown in Jiu Jitsu. And for sure landing on the point of the shoulder as a precursor to rolling would seem to be the worst plan. Talking about rolling is all fine and good, but if you aren't confident in your ability to do it properly (as I am not), you won't. And you won't be able to execute much of a roll if you don't come out of your pedals early enough in the process. The result of a bad try is not likely to be pretty.