It's amazing how often people think that F=MA implies the F is caused by A, rather than the other way round.
The fact that this misconception is so common is even more remarkable when we consider how easy it is to disprove it.
A runner on firm ground is clearly exerting a rearward force on the ground and the Newton3 reaction to that force is pushing him/her forward. But there is no detectable rearward acceleration of the ground.
The same runner on loose gravel is clearly accelerating some of the gravel rearwards, but he/she finds the going much more difficult. It requires much more effort to achieve the same speed.
This suggests that the rearward acceleration is actually an indication of the inefficiency of the propulsion process. It is.