As renewables started to increase, people were saying it wouldn't be possible to keep the grid stable once renewables reached 50%, due to the lack of spinning m

As renewables started to increase, people were saying it wouldn't be possible to keep the grid stable once renewables reached 50%, due to the lack of spinning mass in fossil generators. That obviously has been proven wrong. If I understand correctly, they could have run without any fossil sources on a few occasions recently, but keeping some helps with grid stability. Next step is to reduce fossil fuels to zero for some short periods. But there will be some spinning mass still in nuclear and in biomass generation. Eventually the biomass needs to go too, but each step is good and not completely trivial to achieve.