Xenotime | Science/Coding VTuber, welllll the problem is that you still have to keep in the back of your head that that "not equals" ligature actually has a ! in it that you don't see. If you want to turn it into ==, you have to do this extra mental work of imagining the characters that are there in the file but not there on the screen to replace the ! with a =.

In your example, the <> ++ and -> are fine because they don't hide anything. I only know one example of similar hiding of underlying characters in natural languages — in Arabic, there's this "la" ligature that looks like neither the "l" nor the "a". Fonts implement it as an actual ligature, it works exactly like those >= and != except RTL.