keeping things in tight blocks and subs makes problems harder to introduce and easier to find.

That, right there.

Sometimes, depending on the issue, Perl will inform you of a problem on a line that doesn't seem correct, because it can't accurately figure out exactly what line it really happened on. Parsing Perl is most definitely not a trivial task, and sometimes even the interpreter can't quite figure it out when dealing with syntax issues. Keeping your blocks/subs etc so they fit within a single screen (where feasible/possible) significantly aids in finding these issues.

Throw in a decent IDE or even editor (vi/vim was thrown around) can help with this process as they can highlight the specific issue.

As far as the OP's comment about "prime-time", that's asinine. Other programming languages throw the same way Perl does in this regard in certain situations, unable to identify the exact line number. Heck, I can even get C to do this, so I won't go any further into that FUD, as Your Mother aptly put it. I'll just chalk that up as being claimed out of pure frustration by OP.