I can only guess-
If
a === b is false, then
a !== b is true. always.
But, this implication wouldn’t hold for <==
If
x <== 20 is false, we cannot infer the result of
x >== 20 because it might have been false due to type check, or the relation check.
I think that’s slightly confusing, although there’s plenty of things in the language that are much worse (type coercion in general, to name one).
However, I think a strict < or > would behave consistently.