I think it’s obvious that it is not possible to design an API that conforms to everyone’s expectations, though it is a worthy ideal to keep in mind. But there are other important ideals, such as consistency, and enabling generic programming. Julia Base has broken the “tie” between “define <= in terms of < or vice versa?”. The definition of issorted follows as a consequence, consistently.
You do not appear to be considering all of the other implications of changing the chosen design. Since you are not the OP, it also seems that you have not run into this problem yourself.
If you haven’t already, please read PSA: Julia is not at that stage of development anymore .