General

Stance is essential if you want to do many of the end-game bosses with less stress. Even things as simple as a spawn knocking you backwards in empress can change your whole run if it pushes you into a genesis.

I mean you can technically just keep getting knocked around in chaos pierre or something but it's just not smart since it can knock you into hats sometimes. I guess you could avoid that by up-jumping but regardless, this all translates into:
Less DPS.

Two reasons.
1. If you're dodging, you might not be attacking at that moment = less DPS.
2. If you get killed unexpectedly by a unforeseen knockback, being dead = you're not attacking = less DPS.

With how useful Hookshot is at dodging and maneuvering yourself, it doesn't seem like stance is a must. But if you're not utilizing Hookshot, then you should look into using it more!

I don't understand how people can play without stance on any class. So I vote go get it, note* you need 67% buff duration to keep it up "permanently". But even if it has a small CD it's still nice.

i rarely use it, but it's helpful to have.
ie: Gollux, ht/cht, chaos pierre and other time.

^ if you're range is above average you shouldn't need it. We mostly use it to rid ourselves of the annoyance of getting knocked from a platform or when you want to train without being knocked around at heavy spawn maps.

I have it at lv 1 and I've used it at horntail a lot when I was at a lower range (to not get thrown from plat constantly). Now I just use it at chaos Pierre, gollux, and hmagnus. Without the link I can do just as fine, but I definitely recommend it because it's a fun and useful tool. If you can't get it right away that's ok, stance helps but isn't that crucial to bossing.