Too Long; Didn't Read
The current major trend today is to strive for maximum modularity. This approach makes it possible to build customized environments from a set of libraries and ensure they work almost everywhere. This greatly accelerates the introduction of new solutions to the market, provides portability and fault tolerance, and simplifies load balancing. It also will bring other benefits associated with the transition from the "Pets" model (unique, hand-customized services and servers) to the "Cattle" model (homogeneous entities raised and destroyed by the hundreds).
However, it is important to remember that Docker is a convenient shell over the standard kernel mechanisms. These mechanisms are used not only in the context of Docker but also in conjunction with many other technologies.