No AST was ever used for that. Printing algebra was used in the past, and the new Erlang binary and textual generators both work by appending to a buffer. Your assertion that we need an AST has never been correct. From my point of view it would be wasteful and slow for the compiler to construct this AST just to then consume it to push bytes to a buffer.

RE punctuation, the book-keeping required for the binary format is no less work than for the textual format. All these formats are similarly easy to implement, though the ones that are not human readable are more challenging to debug.