The problem with ignoring trolls, is that often they spread prejudiced opinion as fact and have no facts to back up their opinion. Even when they can be proven wrong over and over with factual data to back it up, they continue to spread the same garbage over and over. Eventually enough uninformed readers read it and think the garbage is fact, and they then start spreading the same lies as well.

Cases in point :
"Most of the homeless are from the mainland" proven wrong year after year, but still widely repeated, even here on CB.

"Most of the homeless are drug addicts", again, proven wrong, but repeated over and over.

One commenter, a few years ago insisted that Rail was going to help solve the homeless problem, and be on time and on budget because it was a federal project and mandated to do so.
COMPLETE garbage, but repeated so many times, voters approved the project.

Ignoring trolls can cause more damage than taking a personal beating by the troll.