Board Thread:Support Requests - Getting Technical/@comment-27704998-20160604211104/@comment-1117661-20160607172729

I think that was the reasoning behind it, there would be no distinction otherwise. It's does come in handy in very rare cases.

Also some wikis use them this way so they show up if the template code is incomplete. It also works as a good visualization on the template page showing where parameters go.

Personally I just wrap the pipe inside so it merges the best of both uses.
 * It'll show "" on the template page, but when used it shows "default" regardless of the parameter being unspecified or empty.