Microsoft sells an entire software system (actually multiple such software systems) that are expensive, and require CALs (per user licensing) and server licensi

Microsoft sells an entire software system (actually multiple such software systems) that are expensive, and require CALs (per user licensing) and server licensing simply to deploy software. Microsoft also provides many different ways to install/deploy Office products for enterprises. In fact, one of the biggest selling point of the O365 enterprise tier is flexibility in deployment/installation options.