The 15 circles and relationships diagram makes perfect sense to me.  My son and I have an ongoing joke that every training class, every conversation, every tutorial, all bypass step one which gives foundational understanding of the situation, grounding principles that one should return to time after time.  For example I see programming as inputting text into a GUI and persisting it to disk.  It is basically moving text around.  The deeper we get into the internals of SQL Server the more we lose touch with reality and the purpose for the applications users are running.