To be clear, this is a renewable problem, not a rules problem.
The problem, put simply, is that renewables don't want to be reactive power sources. It requires additional equipment to properly determine what the frequency of the grid should be (some rely on flywheels, for example) and getting it wrong can be disastrous for the grid and equipment. Effectively, if renewables get it wrong they become a load on the grid rather than a reactive power source. Compounding an active problem.
So, what renewables do instead is follow the voltage wave. If the frequency drops, they cut power to avoid causing damage to the grid and other power suppliers. The thing more traditional spinning disk power suppliers will do is simply power through the down voltage. The disks have momentum which means even if they wanted to, they could just stop producing power. This somewhat self corrects a large reactive power surge.
Grids do not like doing this. This is why they'll charge more to industrial power users that add highly inductive loads (think electric motors, like a saw). They'll even incentivize having these businesses install capacitor banks to avoid adding inductive loads.
The solution is rules, but rules renewable producers have to follow. That's mandatory islanding equipment installs rather than just shutting down power.