They can’t change that. A ladder can’t be a ladder if common statistics sends too many to the top. In other words, they can’t make healers climb with average results without making the lower ratings into empty deserts.
Hence, why skill has to be what makes people climb. But skill isn’t making healers climb as it should in shuffle, because healers, as a role, can’t carry that much. Which is why the design needs to change, to let healers carry.