Dear Junichi,
If you think of SharePont as of document storage (hard drive on steroids), there does not seem to be much to learn actually (think dropbox or google drive)

That is, from the beginning it was thought as office document storage, till 2007 it was even named like this - office sharepoint services.
For Visio, there a several benefits right out of the box - e.g. file history, file view (rendering).
Or you are thinking about more complex scenarios - linking between Visio diagrams and live data for example for building e.g. dashboards?