Compilers like that would go directly from text -> machine instructions, step by step (or to very close approximation) because that is all you had the time and

Compilers like that would go directly from text -> machine instructions, step by step (or to very close approximation) because that is all you had the time and memory for. Modern compilers lex then parse into tree structures and then do lots of mutations and traversals of that tree to optimize in different ways for different architectures, and more code is included at once to make more optimizations possible and on and on and on.