Well, it's not so much using map or grep as some sort of magic bullet replacement for a for loop (they still effectively loop), but more a matter of choosing the right tool for the job. Perl lets you do the same thing in a multitude of ways, and generally none of them is "the one true way". The trick is to find the combination of tools that make the intent of the code clear and maintainable - often execution time is secondary because I/O is the limiting factor.

The mantra is: make it work first, then make it clean, then make it fast (if you need to). "Clean" and "Work" are often related - it's much harder to debug messy code than it is to debug clean code. Consider how easy it is to be off by one in a messy C for loop compared with a clean Perl for loop for example.