"What I learned" seems to missing what used to be shared to every starting web developer; "If you allow user input on public internet pages, people will put vulgar, racist, hacking attempts and worse there, sometimes constantly over long periods of time"

Almost anyone who had a "guest book" had pre-moderation some way or another, or was a tiny-tiny website with barely any visitors. The second the larger cyberspace ecosystem got a whiff of your user-input-enabled website, the spamming would appear.