[necovek]

Sure, UTF-8 is backwards compatible with ASCII, but as you figured out, I was referring to all the 8bit encodings that were in widespread use (eg. HTTP defaults to ISO-8859-1/latin1). And even with "pure" 7-bit ASCII, there is still no reliable way to send an email to неко@негде.срб. You may believe that there are no compatibility problems, but I disagree.

As for maths, I was referring to the fact that notation (signs we express ourselves in in writing) matters, and that further advances in calculus were enabled by using a nicer and more concise character set vs doing everything with "fluxions" and "fluents". You seem to insist on keeping us restricted to ASCII, whereas I am open to exploring new approaches without understanding if there are any benefits first (I am not focused in RoI :)).