i don’t agree at all that lucio is a main healer type of character or a main support, yes speed is incredible but it’s utility and utility is more flexible, you swap utility for what utility your team needs when and where and how.
so while a lucio can give his team speed it’s not always a must, sometimes just being a very mobile healer, and disruption and assassin is enough to give him play over just giving his team speed.
mercy is just worse because she brings very little in terms of giving utility to her team and the healing isn’t enough to off-set it.
but rez is such a slept on ability and really do shine more in the top levels of play and lowest places of play because the skill variance in those ranks isn’t big and when that is the case just having more bodies than the enemy team becomes such a big boon that it swings fights in of itself.