It's really not.

Quotas mean "more than this is clearly too much" not "please use this space".

In good times nobody minds, but in bad times when you just can't extend the drive you have to tell people off. Part of the job of making sure the system can continue to work for what you need it, under _real_ constraints.

You may have to delete stuff, you may have to shut the server down to save power. You may have to limit clock speeds. It depends on the environment and "it really should work because it should be covered by next day on site warranty and you could download more ram" often doesn't apply.