The Problem of Evil/Suffering modified into Buddhism

I have a question about Buddhism, which is similar to or modified from the Problem of Evil or the Problem of Suffering in western religion philosophy: If [ by definition from ordinary intuition ] the Buddha Sakyamuni really had achieved perfect altruistic "merit" or "abilities", then, contradictorily, why when the Buddha Sakyamuni was presenting in the world, the hell is NOT "empty"? --- there were still sentient beings in the situations, such as in the hell, that they cannot meet the Buddha Sakyamuni? Doesn't the NON-emptiness of the hell means there are still rooms yet for achieving perfect altruistic "merit" or "abilities"? Hello everyone. I am from Taiwan. Thank you in advance for everyone who may or does give any constructive/helping information. P.S. Actually I have flagged this my question post as "in need of moderator intervention". Explanation: (1) I was indeed surprised by myself that thoughts questioning the Buddha via the way of reductio ad absurdum came out in my mind (and also written in my question post). (2) I don't have confidence that such reductio ad absurdum is no misleading/misguiding to every kind/level of Buddhism learners.