Clearly, one can obfuscate one's ideas with a compiler language but it's harder. To some extent one is talking about what one wants rather than how one wants to do it. The trouble with machine code, of course, is that when you look at a random section of machine code you don't know what properties of the instructions the programmer really wanted to exploit.
"PL/I as a Tool for System Programming", Datamation, 15 (5), 6 May 1969, pp. 68–76