Hopefully you've been able to read Part One that covered the features like app launcher, cloud UI, OneDrive for Business, Search, Sharing, and Durable links. No, there was no particular reason how these features are divided, it just worked out that way. Let's jump right in.
One of the first limitations that SharePoint administrators encounter is that of content database size. Content databases can start at a reasonable size, but over time get larger and more bloated as new content is added – impacting performance and responsiveness.