The reason I said that is because single leg squats are not just about balance. They are about stability at the hip and ankle. They teach proper firing, etc...
Balance and stability are not the same thing. Keep that in mind. Balance is "equilibrium". Stability is more like resistance to movement. Anybody can do static split squats and lunges, etc...well with not very much practice. And while I can sing the praises of any single leg movement all day...as I often do, haha..."mastering" the single leg squat puts you way far ahead of the game. Not that you can't work in both...you can if you want. Hell just "practicing" the single leg goes a long way.
But while split squat variations require a balance component and they are "uneven" so you get that kind of core component, along with so many other benefits you are "somewhat balanced" and "somewhat stabilized" the whole time. Even with lunges your never exactly doing it on one foot since the weight is being shifted in a mechanically favorable way..i.e. a natural way.
But let me just say, for perspectives sake, that it was just a casual comment as far as my druthers. Most people don't do any sinlge leg stuff at all! I can hardly argue single leg squats versus split squat variations without pointing out that just DOING single leg stuff in the first place is one thousand percent better.
BUT with a static supported or dynamic supported single leg movement the glute medius and hip rotators do not really have to work to stabilize the hip and prevent internal rotation of the femur. Whereas with single legs squats, UNSUPPORTED, they do..which has obvious benefits for knee health and not just proper hip stability. It's all a chain, after all. There is a lot of need for core bracing. It take real strength to do it. etc and so on. A single leg squat will actually carry over, imo, to a static split squat and hence to a later progression to lunge variations, imo, but the reverse is not true.
And I know it was just a question, btw, Crade
. I don't take every query as a challenge!