I'm not sure whether I disagree or not. To wit:

$_ = "abcde";
if (/(.)(.)/) { # first two
    if (/(.)(.)$/) {
        print "inner: $1 $2\n";
    }
    print "outer: $1 $2\n";
}
print "outer: $1 $2\n";
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$1 and $2 aren't localized within the if block -- unless the regex is also within the same enclosing block.

(At least, that makes it more explicit.)