volatile is mostly useful for telling the compiler not to optimize out a variable. For example, if you use memory-mapped I/O, you can mark a pointer to it as volatile to tell the compiler that the hardware will be changing it and it shouldn't make any assumptions about that while optimizing. That's lower level than most people go, though, so I understand that it's not useful for the average C programmer.

> I guess the designers of C realized there are better alternatives when implementing their own compiler.

Or maybe they went off the rails and lost their minds, like Bill Shockley.