Writing bigger programs I struggled to understand what I wrote without comments on every line describing the stack. One could use more variables to make it easier to understand, but in the old days that would also make it less efficient. I would frequently have to reverse engineer my code.

Interestingly, object oriented PostScript would tend to help make your code seem more like prefix code, because it would be like more like "object method argument ... send" rather than "... arg arg function".