Is there a group of people who decide what the next boards hate champ is?

wait til the updates its gonna be talon and kha

Yes. I am on the Board of Champion Discussion Propagation, and we use a variety of factors in the process to decide what champions will be actively discussed here on the Gameplay subforum.

With the discussion around Yasuo becoming stale, we chose three champions to be discussed in his place. The first, Syndra, was to take Yasuo's place as a target for unreasonable QQers, and serve as the current figurehead of unbalanced, overpowered, low-counterplay picks in League.

We also wanted to choose a counterbalance, someone who people would unreasonably declare weak, and seeing the new Edge of Night item on PBE, we decided it was time for Karthus to receive some attention. We are happy to see that Karthus is fresh in the minds of Boards posters despite his incredibly low pick rate in game.

Lastly, we chose another champion for players to hate on, because the hate for Yasuo was too large for only Syndra to handle. This time, we picked Jayce, because ranged top laners are an easy target for hate. He also gets picked competitively. So OP.

You're thinking of the LCS

It's pretty random, a good 50% of the time it's BS too.

MEANWHILE AT THE LEGION OF DOOM

It's called the pro scene

they're in the lcs, which is one big scheme to show off what champions us people of the boards will hate