That is why they tell you to not stop focusing on the road as you use it.
I had to drive a modern car home once with the power brakes malfunctioning and I couldn't exert enough force (grabbing the steering wheel to give me leverage) to have safe braking power. I ended up going very slow in the emergency lane of the highway in second speed so that motor braking could help me stop. It was not fun.
And yes, standard transmission. I was coasting downhill in neutral, with the engine etc off. Testing the running start protocol, for dealing with battery failure.
i suggest this thing is mainly going to be a problem where the power-assist fails during a trip at some unpredictable and unfortunate moment. driving where you know you won't have power-assist for the entire trip would be far safer.