This is an awesome paper on the importance of the intrinsic foot muscles. Getting a nice comparison to how our intrinsic back muscles work with lumbopelvic control. The Foot Core System.
One more reason to be doing kettlebell swings. They help to improve the stability of the lower back.
The top portion of the kettlebell swing is a standing plank. Remember that. Optimizing Back Health with KB Swings.
"Don't put moral judgements on any exercise." Dan John.