Someone has not followed many SwSh "raid events" I guess, since the previous ones featuring legendaries were the same.
These events are mainly designed to give players a challenge and a reason to play with friends (the mewtwo and zeraora raids in the past were pretty monkaS and kinda required to go there with a plan), though in general the hype has long died down and I don't see them bringing players back to the gen 8 games anyway.