>>8467324They seem to be rarely used (I almost never see people use them in photos or displays even for lines that have them), they are another consideration in the budget of the toy that could go to something more useful, and they can potentially introduce a number of problems, like floppiness, uneveness of the bottom of the foot, or in several memorable cases, even companies who do not understand how they work at all (for example, see SHF Luffy's feet, where the giant rectangular hinge pokes out the wrong way so the toe joint is unusable).
