This Practice is to encourage the use of a for loop instead of while plus a counter. It reminds us of redo, a Perl feature I always forget which lets us do the loop over at this iterator. If the only place the while loop does not increment is to try again, a redo fits perfectly. If the loop has to do more complex changes to the iterator – back up, start over at zero, whatever – then you’ll sill need the more complex while+counter.
I always forget redo, which is embarrassing. It’s a core feature of Perl, and a useful loop control mechanism. It can make complex structures easier, and that’s an excellent reason to know it.