The main reason I use muriatic is because of it's low cost and easy availablity.  I have enough brain cells  to manage the risks with the product, so that's not an issue for me.  (I also reload pistol ammo- make bullets from melted lead, handle gunpowder, AND I EVEN DRINK COFFEE FROM MCDONALD'S!  and still have all my fingers, toes, and both eyebrows- go figure).
 The alkalinity of my tap water is off the charts, and it's nice to add a relatively small amount of muriatic instead of 3 or 4  spa sized containers of decreaser, at about $6 each.  Used to cost me over $20 just to balance the water.  Now it only costs a few pennies, and I'm adding less "stuff" to do it.
But if I only had minor adjustments to worry about, I'd pay for the spa packaged decreaser products. Â
By the way, muriatic acid doesn't seem to freeze, at least in winter temperatures in MN. Â I forgot the container was outside since my last water change, and despite several below zero nights, it didn't freeze.