Forgot to mention, but I also agree phone users are worthless contributors and nothing more than mindless consumers and responds with 1 sentence using buzzwords or catch phrases to stroke their ego. However, it can be nice to mindlessly surf and read on the toilet and reply from a computer later so you'll want to cater to those because someone may discover your website while on the toilet. One way to prevent posting is to use a useragent or window size css detection to disable posting from mobile by throwing an error or just hiding the post form.