Old techniques are not necessarily more fundamental, they are just more primitive. (And often, but not always, more efficient.)
In particular, old compiler texts will often do things like emit code directly from the parser, try to minimise the number of AST passes, or keep complex global symbol tables separate from the AST. These are mostly workarounds for technical limitations that are no longer relevant, and in fact only obscure the principles being taught (code generation during parsing is my pet example of this).
In particular, old compiler texts will often do things like emit code directly from the parser, try to minimise the number of AST passes, or keep complex global symbol tables separate from the AST. These are mostly workarounds for technical limitations that are no longer relevant, and in fact only obscure the principles being taught (code generation during parsing is my pet example of this).