Long talk about nothing. Seems like somebody was trying hard to pull minimum 2000 characters limit on the article.
Repeated talks about showing hidden files for no apparent reason, useless advice about backups.
The essence can be summed in just two phrases.
%AppData% is a roamed persistent user settings.
%LocalAppData% is non-roamed machine-specific settings or other discardable kind of data.
And of course you want to backup %AppData% (but not %LocalAppData%, unless a braindead developer put persistent user settings in there).
Oh, and of course, you can directly enter "%variable%" into the Explorer address bar. If a variable resolves to a filesystem path, it will attempt to start the application (or show a directory, which boils down to "starting" it, in a sense).