You can read about why Ian made the new knot as an improvement over secure knots specifically here. [0] But hey, maybe Ian was unknowingly tying a Granny knot instead. ;)

    Comparison To Other Regular Shoelace Knots
    
    It was much easier to prove that Ian's Secure Shoelace Knot is more secure than any of the regular shoelace knots. Using a pair of shoes with round, slippery laces, I tied one with my Ian Knot and the other with my Ian's Secure Shoelace Knot. Despite tying both to approximately the same average tightness, the Ian Knot came untied two or three times a week whereas the Ian's Secure Shoelace Knot never came untied.

https://www.fieggen.com/shoelace/secureknottech.htm

I think for most adults avoiding a granny knot is enough. But my son is not yet 10yo and he often has untied shoes at the end of the day.

I've even tried tying his shoes myself (so I know both the knots are pulled really tight, and that the loose ends are the same length as the bows). Even so, somehow the ends get pulled hard enough that they end up undone.

(Somehow for him even the Ian secure knot doesn't guarantee a full day without laces coming undone.)