Notation is a tool of thought and of communication. The clearest example of infix botching both is probably perl style regex.
Postfix is interesting in forth. It makes the stack manipulations very easy to reason about, and the stack is very important there so this looks like a win. The cost is in coherently expressing complex functions, hence the advice to keep words simple. The forth programmers are doing register allocation interwoven with the domain logic.
Lisp makes semantics very easy to write down and obfuscates the memory management implied. No thought goes on register allocation but neither can you easily talk about it.
Discarding the lever of syntactic representation is helpful for communication and obstructive to cognition. See also macros.
Postfix is interesting in forth. It makes the stack manipulations very easy to reason about, and the stack is very important there so this looks like a win. The cost is in coherently expressing complex functions, hence the advice to keep words simple. The forth programmers are doing register allocation interwoven with the domain logic.
Lisp makes semantics very easy to write down and obfuscates the memory management implied. No thought goes on register allocation but neither can you easily talk about it.
Discarding the lever of syntactic representation is helpful for communication and obstructive to cognition. See also macros.