Why? When you post a single question that gets downvoted you don't get banned. It's only when you repeatedly ignore the rules and ask terrible questions over and over refusing to learn from your past mistakes.

There might be a discussion to be had about how to teach users what a bad question is, or how many is too many, but I don't understand why we should let people who repeatedly fail to clearly ask a question keep asking. Most people have no such problem.

In fact, when experienced posters politely point out what the rules are and where to read more about them, you start to see new posters fall into 2 categories:

   1. The people who say, "Oh, I didn't realize that's how it works. I'll update my question/do better next time/etc."

   2. The people who insist that no, it's their platform and they'll ask whatever they want however they want.

People in category 1 usually have no further problems using the site. People in category 2 usually end up banned.

And of course, there are experienced users who are jerks and don't point out rules or don't do it politely. They should not be excused. But letting new posters continue to pollute the site with terrible questions isn't going to help anyone - especially not the people posting the question.