While that's true, there is some market clearing price in which the activity just ceases to exist.

For instance, take something with a small marginal benefit like a dedicated person at a supermarket to bag groceries. It's a nice to have but the value to the employer is probably less than a $15 minimum wage. So you could say there is a shortage of grocery baggers since there is no one willing to do it at a market clearing price.

Doesn't mean we should do anything about it. There will always be some extra activity that would take place at a lower price, but it's worth while to notice that.