If efficiency matters at all to you, then yes, traditional squatting has benefits over single-leg movements. If coordinated effort between both legs simultaneously has any relevance to your goals, traditional squatting has benefits. If developing maximal overall strength has any relevance to your goals, then traditional squatting has relevance. You will come across limiting factors outside of leg strength itself if you avoid squats altogether. There is only so much weight you can reasonable hold in your hands performing split squats and pistol squats. You also have to dedicate far more effort and training energy towards balance when performing single leg movements, that could otherwise be directed simply at moving heavy weights.
The bottom line is that if your goals are quite modest, you can likely get away with just single leg movements. I don’t see very many, if any, goals you could have where traditional squats wouldn’t benefit you, but all that means is that you’re likely taking a less efficient path to your goals, you may still get there.