Except that you don't get proper OO lookup/inheritance. I suppose if all you're doing is regular procedural stuff, it works OK. You could try B::Lint, which for this program:

use strict;
my $flag = shift;
sub hello { return "hello by reference\n" }
print xello() if $flag;
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prints this diagnostic:

$ perl -MO=Lint,all blint.pl
Undefined subroutine xello called at blint.pl line 4
blint.pl syntax OK
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