All the arguments about it not being safe to stop when turning off busy roads - presumably you’d stop for someone who has started to cross the road who is elderly or disabled, crossing with small children or for any other reason moving more slowly than average? You’d be able to do it in that situation, right? So why is this any different?
The difference is that in the old system, the pedestrian does a risk assessment, checking to see where nearby cars are going, and whether they have time to cross. So, unless the pedestrian is not paying attention, or it's a junction with poor sightlines, they are rarely in the road when a car is turning in, and so cars turning in rarely have to give way.
In the new system, the car will have to give way a lot more frequently. (Or would, if they followed this system...)