Container Engine should not only one machine type
A cluster should have multiple machine type for various purpose (maybe CPU-intensive, memory, IO...). I can use label to select the machine type to match my purpose of pod.
Lisandro Antonio Rafaelano Colocho commented
sure Maybe in 2016 there weren't the concept of nodepools.
Chris Hodapp commented
This exists in the form of NodePools, which a cluster can have many of.