Well, I’m not Filmore, but here are some that I think resemble what they are talking about:
Sam Stone pitted for gullibility re: Trump, expanded into a general pitting of everything Stoney
This thread about MordecaiB began with a pitting about board wars, but shortly morphed into an omnibus pitting, including someone urging everyone to “heap more scorn” on MordecaiB
This thread pitting octopus for…something , I don’t know, quickly turned into an omnibus bashing thread
I’d like to make it clear that I am not defending these pitted posters or arguing that their pittings were not “justified,” whatever that means. I strongly disagree with all three of them on just about everything. However, when I read filmore’s description of pittings “becoming a Festivus pole for airing of all grievances against the person,” I knew I had seen this happen many, many times. I can’t believe that anyone who spends regular time in the Pit would suggest it doesn’t happen. If I had the time, I’m sure I could link to many more.