Stabilizer muscles were a big buzz word back when I first started working out. They were a point made by

free weight guys like me in the debate over free weights vs machines.
When the functional movement craze hit a lot of focus was placed on working these muscles through things like balance boards and unstable positions like standing on one leg. For a short time, it seems like working your stabilizers was the magic bullet for everything from building muscle to preventing injury.
And then the boom was lowered and they fell out of favor.
Experts flocked back to the heavy weights and even the machines claiming the whole functional training and stability muscle thing was nothing more than a fad. It was a gimmick and now we know better. I’ve even heard some coaches claim stability muscles don’t exist at all and that things like balance and stability have no place in helping you get stronger.

I’ve been through the run around myself and I’ve now come to the conclusion that not only do stabilizer muscles exist, but you’re screwed if you ignore them. Forget about becoming bigger and stronger. All of that speed and power you want will be a fantasy too.
Like calories, stability muscles are important and they do count. Our struggle to make progress through using them is the fault of our own understanding of what they are and how to use them. It’s not because they are some outdated fad that we’ve wised up from.
Check out this video to learn exactly what they are and how to use them properly with all exercises: