Two reasons. With an algebraic system, I have to plan ahead and add open parentheses, or reorder, to do what I want. With a stack, I can always push/dup, then r

Two reasons. With an algebraic system, I have to plan ahead and add open parentheses, or reorder, to do what I want. With a stack, I can always push/dup, then roll or pop back. It’s the same reason I like having function calls and a call stack when programming, compared to APL. Second reason, RPN systems are typically open: I or others can add operations. That’s pretty rare in an algebraic machine, though not completely nonexistent.