Hooks are easy to produce in aluminum. Make a die pattern that includes hooks. A one time cost. Extruding through a more complex die might be a touch harder but that's it. Bend your hooked rim to a circle, plug or weld. A touch of filing maybe and send it out the door.

CF - much harder. The mold has to come apart into several pieces just to remove each rim. Added labor, fit issues, probably shorter usable mold lives. So convincing the public that simpler, lighter and stronger is a no-brainer (at least in the stockholders' views).

Thank you Silca for your rational opinion not influenced by the fads of recent decades.