1-Saves brass
2-More consistency (keeps it at the same ductility through each firing, sizing, ect., instead of get harder).
If you don’t want to spend $1500 there are other methods. IMO, the amp or similar is best bc it’s electric, then a flame annealer, salt bath.
I have an Annie Annealer and like it for what I do and for the price.
With the salt bath, I wouldn’t trust myself with a hot ass liquid.....I’d burn my dumb ass.
Flame, is what I wanted first off since I’m a pyro but to have one in the winter in a non ventilated space, I don’t trust it with the fumes and it can be tedious to set up.