I think it's a great new rule.
I recall reading a study by Pelz about 30 years ago that said he did an in-depth study and his recommendation was that us amateurs...should
always leave it in (when possible back then).
He posited that the stick can/will slow momentum, thereby allowing gravity to have a better chance of overcoming inertia...thus a better chance of the ball falling in the hole.
As for those who try to jerk the ball out of the hole using the flagstick, I've had to stop a number of experienced golfers that I play with often (who DO fix ball marks/rake bunkers/sand divots) from doing just that...and
should know better.
I've even offered to get their ball for them, which is usually enough to shame them into bending over...and picking their ball out of the hole by hand.
I've been toying with ideas on inventing a device, such as the current suction cups, to put on the end of putters that would get the ball out of the hole with the stick in...without damaging the hole.
And as I point out to those who try to jerk it out with the stick, a lot who already have the suction cup on their putter handles, why don't they just pull the stick...and then use their suction cups?
First world problems and struggles...are real.
