It used to be that anybody could post anything on the Internet. If it was something illegal sooner or later the state FBI/a Judge/Whatever would come for you, but it was a matter between you and the law. Your Internet provider, your hosting provider, etc. couldn't care less because they were not involved in your activity, in the same way that the post office is not to blame if you send an explosive letter using their service.
That's Section 230. While it's an USA-specific law it was in the spirit followed also in most of the other Western countries.