I disagree entirely about safety. Yes, when driving normally, nothing untoward is likely to happen, but I had an incident in my car when I had the adjuster cups out.
I needed 2 new tyres, and when the garage jacked the car up, the springs became unseated at the top point, so when the car was lowered to the ground again, they weren't in place properly. The whole of my car was resting on the exhaust basically.
I never had any concerns before because my car had never left the ground so I didn't even think to check it before driving. The noises coming from the rear end of my car were enough to almost cause a brown pants moment! Took it straight back to get it sorted.
I've since put the adjuster cups back in, and raised them about and inch and set the fronts to match. Handling has improved massively, and my rear passengers just about get away without a need for a dentist afterwards.