You will find the vast majority of us on the forum with SWCG would never have a pool without one. They add the chlorine your pool needs every day. You still need to test often, adjust the % setting when needed, check pH, TA, etc. But not having to carry liquid chlorine home, store it, add it every day, makes them priceless in my book.
Pool builders do not like them because many pool owners do not manage their pool water chemistry. They have a pool 'service' do it and they then have issues with scale, poor pH management, etc. Do your own pool service. Get a robot to clean the pool.