Why not use cardView as root element?

Question

Android

In all the examples and tutorials that I have seen, cardView is used as a child element:

<LinearLayout>
    <android.support.v7.widget.CardView/>
</LinearLayout>

Or

<RelativeLayout >
    <android.support.v7.widget.CardView/>
</RelativeLayout >

I made the root cardView and did not see any difference, so why do they do it in the tutorials?

Answer 1

patamushta:
1) 85% of tutorials do not stand up to criticism
2) a rare screen consists of one CardView (add some kind of navigation drawer, fab thread, a search bar that disappears when scrolling, or something else - the issue will be resolved by itself)