To be fair, the post does not say that. It says that it's "one of the papers significant to the author" - a subjective ranking.
I loved this paper. It's a good example of a VAE+RNN style model learning for MBRL. It's well exposed. Sure the results aren't the best but it's a well worth read.
Which are the top three mist significant RL papers?
Other than the AlphaZero papers and DQN, maybe TRPO? (assuming we're talking about deep RL)