There may be more than one exit.

There will be only one that is neither preceded by indentation nor followed by an exit code, so that it could match ^exit$, unless you contrive some hypothetical nonsense purely for the sake of contrarianism.

Any reasonable person will indent a conditional exit within the block testing its condition, and more than one unconditional exit doesn't make sense.

It would still make me uncomfortable that a 2nd exit or lack of indent would break my script. And it's less clear than an explicit marker

Ah fair enough. I didn’t think about using the indent, that’s pretty clever.