It wouldn't help much. If someone were to get banned only once a month or so, it isn't a hassle to keep creating emails. You just verify your account with a new email then never use it again. Even having to do that every day wouldn't be a hassle.
If they were to make that rule, I think the number of times you can sign up should just be limited to 5 (to prevent spam, but still allow other users to restart and choose a different name or their correct age).
In some circumstances, it is a great thing to be able to do. I've deactivated two accounts since being on here. The first time was because I told the site I was 19, since I wasn't sure at first if minors were allowed to use it. Then, I ran into some negative but frequent users on my second account and I got into an argument with them. I felt too anxious to continue that account.
I don't want to involve my private emails on websites because you're more likely to receive spam, so I only use one email for every social media that I have. The less you use an email, the less spam you get from various websites. Basically I have two that never get used, and those two never get spam, while my main email always does.
There's hardly a point to making that rule.