{{tl}} should be substituted.
Does it work when substituted now? I know there were some issues with
that before.
In any case, if we were to do this, we would need a bot to go through
and substitute the massively-used shorthand templates: {{tl}},
{{user}}, {{vandal}}, {{admin}}, etc.
The point of these templates is that they are short and simple to use.
If they are subst:'d in, they become more complicated. Why do we need to
do this?