Guild war was all about total guild activity and buffs. Backup and prayer both buff speed as well as the other stats and the paid exclusive senki don't have enough of an advantage over that. My normal attack team was 2 from free gacha, one from campaign reward, and one inhuman.
Game was not very f2p friendly in it's early days and I think they burned so much of that player base that it wasn't viable for them to figure out how to run it once smb left.