The reason why people are using not limewater alone is quite simple: for SPS stuffed tanks you would need more of the ( only little concentrated) limewater than your tank is evaporating each day. So you can’t always adapt your tanks consumption alone with limewater
So in your opino
I personally am a fan of using only one method instead of combining two as it is less confusing and less maintenance work to do. So why not only dosing? Or only Ca reactor ?
All-In-Ones like CarboCalcium and others are not as flexible as 2-part dosing (ca and Alk can’t be dosed separately) and are also more expensive. So why should you choose this? Maybe if you are running a Nano..... not for a bigger tank