I think the purpose of the new rule is to prevent devices, which tell the racer how far away they are from the line and how long it will take to get there, or tells them when to tack, from being used during the actual race.
As I understand it, the proposal wants racers to use their brain power to achieve the best result and not achieve it by the use of (very) expensive electronic devices. So banning the reading of devices when actually on the water would achieve that. Reviewing the data afterward may help the racer to make better decisions when they go back out again on the water. What’s the harm in that?
I’ve only started sailing and racing this year, but it didn’t take long to realize that a good start followed by decent tacking and an awareness of currents,tides and tactics is far more useful than having a box tell me what to do. Haven’t succeeded too well so far but… I’ll endeavor to persevere.
I would ban the use of devices which give start line bias and best tacking information while actually racing, while allowing them on-board (but out of view) for recording of the boat’s track, speed, distance sailed etc, for review off the water.
The difficulty with banning them from being on-board is that GPS is available in tiny devices nowadays and an unscrupulous fellow can hide them pretty easily.