Most websites have a rules page that can be seen here:
If you wondered why your post was deleted, it probably violated rule #1. Most of the posts we've deleted are either out-right spam or are using hate speech just for the sake of using hate speech.
There are other Multichan servers who seem to allow spam or hate speech. Go use one of them, or consider hosting your own server where you can be assured that another person's conflicting moderation philosophy won't spoil your fun.
We rarely ban users, thinking that deletes will generally get the message across. It's worth reminding the community that use of https://0chan.vip is a privilege, not a right. Although Multichan is public domain software, meaning you can use it for whatever purposes you want, https://0chan.vip is a private service offered by the developer to demonstrate the software's current state of development, and to allow interesting people to have interesting conversations in a relaxed place. Your posts or ability to post may vanish at any point for any reason. If you try to be a good community member, though, that probably won't happen.