Having been a moderator before it was easy to impose such restrictions, I'm very glad for them. It was effectively impossible to ban anybody because account creation is so trivial.

And yes, it's important to be able to ban people. Even the subreddit I moderate that's dedicated to a niche hobby and populated almost entirely by nice, helpful people has had an incident or two of serious targeted harassment. Those that touch on more controversial issues or potentially involve money have a high volume of abusive behavior.