This was the previous discussion: [Draft] Rename Sequence.elementsEqual - #108 by Adam_Kemp1 (starting with my first comment explaining the complications involved). Eventually it ends up with someone suggesting new language features just to make it workable.
I should say I made some mistakes in my explanations, but I don't think those mistakes invalidate the argument. Having two sequence types (one ordered and one unordered) is just not going to be easier to use. It will be much harder to use.