Oh, wow, what a revelation! You've discovered that spectators can be clueless. Who would have thought? It's not like we've all experienced that before.
And yeah, because shouting "GET OUT OF THE WAY!" is going to magically make a rider suddenly regain their composure and ninja-jump out of harm's way. I mean, it's not like they're already stunned, hurt, and trying to process what just happened. Nope, a loudmouth in the crowd is all they need to snap out of it.
And let's be real, staying quiet and letting the rider get up at their own pace is way too sensible. Where's the entertainment value in that? The crowd needs drama, and what better way to create it than by yelling useless instructions?