It all depends on what you want to achieve. And if you remove the rules, there's pretty much one thing you'll achieve:
Warning. NSFW content, activities you may find highly demoralizing, and generally the cesspit of the Internet.
/b/.
Currently, 4chan lost a lot of its teeth. There are quite a few rules restricting the board, but still these daring to look in there will get a clue about the result. But several years ago, it looked quite differently.
As various boards of 4chan had different rules, the rules for /b/ were:
"ZOMG NONE!!!1*".
Note: "ZOMG NONE!!!1" applies to moderators as well.
The result is something that can be... scary. Let me give you an example. A thread cheering a girl committing suicide due to the /b/'s prior activities: They stole naked photos of a teenage girl they from her flickr account (exploiting some weakness of flickr allowing access to private albums), then found her personal data, contacts on facebook, and sent these photos to her school, school friends, parents, her boyfriend, all with quite malicious derogatory comments.
That's as low as it can get. Are you willing to handle that?
