For the research that i have done, i think this is a element that is no longer in use. It has three uses in the code as of 2.1.3:
30: <item name="childrenFromMeta" xsi:type="boolean">true</item>
24: <item name="childrenFromMeta" xsi:type="boolean">true</item>
10: <item name="childrenFromMeta" xsi:type="boolean">true</item>
But you might notice there is no view model that also has this value. Now, not all elements have a direct usage in the code, but it's the first hint that this was once used and is no longer there.
Digging a little deeper, i found this commit: https://github.com/magento/magento2/commit/288f9a2af104c67ffe6eba3ffef98e39c7b9acc9
Which shows the assigning of the value
const CHILDREN_FROM_META = 'childrenFromMeta' in lib/internal/Magento/Framework/View/Element/UiComponentFactory.php
But if you look at this file now, that has since been removed. I'm sure if we dug into the file, we could find out what this originally did, but at this point i think we are safe to say that this is not longer in use and should have been deleted.