It's a big place—in real life and in Dunbar's poem. The world also has a responsibility to recognize the suffering that occurs not just in a personal sense, but a worldly one too. Unfortunately, the "world" often ignores the kind of suffering that doesn't immediately affect it (specific people/places). But by keeping things universal thematically and stylistically, the speaker is suggesting that it's all connected. So ignoring problems doesn't keep them away.