Why would you expect two different technologies to advance at the same rate?
Simply put, quantum computers can be immensely more powerful but are immensely harder to build than classical computers. The theory of their operation is more complicated and based on recent physics, there are greater theoretical pitfalls and obstacles that inhibit their scaling up in size, and their design requires much more sophisticated hardware which is harder to engineer.
Nearly every stage of development of a quantum computer is inanalogous to that of a classical computer. So a question for you; why compare them?