what if someday the default for $| is instead 1?
That's not the problem: 
$ perl -le '$| = 1; $|++; print $|++'
1

[download]
The problem is that it might confuse someone who doesn't know about this particular piece of DWIMmery.

Update: removed unfunny joke

In reply to Re^2: Poor Perl Idioms Explained (except not really) by robin
in thread Perl Idioms Explained - $|++ by broquaint

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