It is more difficult than many think mate - they often come back, hiding and biding their time - and also in greater numbers. Though there were seemingly too few mods on there to make a dent - let alone a difference - and it became part of the culture of those boards.
For me, there needed to be enough mods on there to try and change that culture - to effect that change.
Some the racist, sexist, homophobic posts on there were awful - only when the higher-ups at IMDB started to feel the pressure (and the brand was started to be considered as toxic) did they try and seriously address the situation… (they had infected foot - which needed some care, effort and attention - instead they chose to cut the body in two and throw away the lower half).