Why? Because it no longer has a permanently attached (captive) output cable. Those wrapping hooks were for "cable management", so there would not be a long cable dangling in a bag or carrying case. A discrete USB PD cable is much easier to manage alone, than a dangling captive cable.
Yeah but you'd have to use a rubber band or something
Every manufacturer recommends against doing this and even warns you to do it. This is THE way to destroy your cable because you are wrapping a warm cable around a warm power adapter. When it cools the cable will shrink and the wrap will be too tight. This causes increased wear and tear on the cable which greatly reduces its lifespan. Never ever do this with any power adapter whatsoever! The prongs on the older Apple power adapters should have never been on the power adapter at all. They finally get rid of them.Or wrap it around the brick and tuck in the end. That's what I do.
From a design perspective: In order for those hooks to work one end of the cable needs to be fixed to the charging block, and the other end needs the small "U" shaped part to connect itself to the cable.
The removable cable is a much better design as wrapping those hooks tightly guaranteed you'd need to buy a whole new power brick after a couple of years.
I use Velcro cord wraps on all my cords - example (only $10 for 100):