People never learn using an OS - they learn to use applications. The OS needs to be less intrusive as possible. Any OS that gets in the way requiring complicate hops to perform basic operations will go nowhere. Most people are not IT techies, and see computers just as something they have to use even when they would like to work without. Moreover, applications may be far more complex to use than an OS (from a user perspective), and "reskilling" user to use different applications with different GUIs and workflows can become quickly quite difficult and expensive.
While in large organizations IT people need something that can be easily deployed, configured and maintained remotely.