Saying Reservation is keeping Caste alive is like saying laws are keeping crime alive. Or that medicine is keeping disease alive.
It's like saying Laws are making criminals commit more crime and that if we abolished law, criminals would stop, or that if we stop using medicine, germs will leave us alone. It's like saying germs are a thing of the past and that infections only exist because we use medicines and inconvenience germs.
This hatred of medicine is not just a metaphor BTW. Because we have heard it already. Wanna guess who uses it?
Conspiracy nuts and anti-vaxxers, that's who! The habit of blaming solutions for the existence of the problem literally fits the conspiracy theory template. It has always been a favourite mode of mass nuttery by those who don't like to address the root of a problem because it inconveniences their privilege.
The root cause of this particular problem, and the problem itself, are standing in broad daylight as everyone looks this way and that way while whistling music from 2000 years ago. It's casteism.