The thing about RPN is that it worked well as a sort-of "spoken not written" language. It's a clear and usable way to give instructions one-at-a-time to a calcu

The thing about RPN is that it worked well as a sort-of "spoken not written" language. It's a clear and usable way to give instructions one-at-a-time to a calculator with a 1-line display. But written out on paper, it's very hard to see what's going on at a glance, which is why nobody does this on paper. Almost anyone programming in mathematical expressions of reasonable complexity today will spend much more time reading (and triple-checking!) these expressions than typing them. That's a strong reason to like infix notation, and in general notation close to what you would use on paper.