ASCII is enough to write English, or, at least, it used to be back when ASCII was a multi-byte encoding for Latin! I know, it sounds crazy, but it used to be a thing to use over-strike using back-space. E.g., ë was e BS ", ø was o BS /, etc. It was a thing back in the days of typewriters. I believe this is the reason that upper-case letters in Spanish are allowed to be written without accents even when they are needed otherwise, that accented upper-case letters were hard to produce with typewriters and ASCII fonts.