Core training gets reduced to crunches in a lot of beginner routines, which misses most of what a genuinely strong core actually does for training and daily movement.
Anti-rotation and anti-extension matter as much as flexion
Exercises that train the core to resist movement — like planks and anti-rotation holds — build stability that carries over into heavier lifts far more than repeated crunches do.
A strong core protects the back during other lifts
Most compound lifts depend on core stability to protect the spine under load — which makes core training a supporting piece of nearly every other part of a program, not an isolated add-on.