I want a Rioter to explain why the new project game mode is adc only?

I want a rioter to give me a decent explanation as to why only 4 of the entire project line up can do the project game mode. It makes zero sense. Absolutely none. Why make a game mode, call it project, then not let the majority use it. Yi Zed Fiora Kat Ekko Leona Yasuo, cannot use it. There are more project Melees than project adcs, and they can't be played on the new map made specifically for the project universe. I want a Riot explanation. It's like if in the SG even you could only use melee champs. It rules out the majority of the skins. It doesn't make sense. Until a rioter can convince why they made this awful choice, I will believe it's simply more adc pandering.