My post was deleted, according to the moderator I was promoting myself.

What is the point of deleting a post which shares a tutorial? the moderator deleted an article where I was sharing an open-source project (Yes, free for all), according to him I was promoting myself or my website, then the question came why this post hasn't been deleted? (No I don't think it should) https://www.reddit.com/r/softwaredevelopment/comments/ulpmqz/i_created_a_website_to_generate_code_snippets/