How can Edgar Allan Poe be considered the greatest poet?

Edgar Allan Poe is not considered the greatest poet of all time... in fact he was very unpopular at his time.. only after his death, he became renowned. The modern people like his works due to its stark nature, a lot of it are psychological thriller, and people love it. I guess a lot of people can reflect on his works. He also wrote the 1st detective story/poem thing so that is pretty significant