It would be useful to the user to warn them before there account is disabled from posting questions. User doesn't realize that they can be actually be barred from posting questions.
My account was disabled on ServerFault, for reasons I now understand are valid. In my case I came to know the reason after SF stopped taking questions from my account. On SO I am a normal contributing member of the community.
Now I tried improving my questions, try to contribute to the community, etc.
I still have a legitimate question for SF, but I'm waiting for my account to reactivate.
If I had been warned of the impending consequences of my misunderstandings I may have avoided all this in the first place is the point.
Hey if you keep deleting your questions we're gonna assume something's wrong!