if you go back to the fundamental justifications for having databases (right back to the days hierarchical Dbs for instance) the whole thrust was about data management approaches that would break down isolated "islands of information" that bedevilled the corporate landscapes and caused no end of inconsistencies and confusions.

The schema concept being challenged here came to the relational world in Oracle's products - it was a pretty silly idea then and frankly it still is - because it tends to reinforce the "islands" type thinking. But hey, I won't just bash Oracle for it - if there was a stupid idea lying around then for sure M$ would just have to adopt it too now wouldn't they?