Chekhov was very popular in Russian schools up until early 90s because of his writing style. You're absolutely spot on that he writes in very plain Russian. Dostoevsky has some mindfuck-inducing way or getting across to the reader. His writing is difficult even for a lot of native Russian speakers. L.N. Tolstoy also has some easy reading ( Детство. Отрочество. Юность / Childhood, Boyhood, and Youth is my favorite)