Why use a DI virtualType without an explicit type?

From the Customize using a modifier class tutorial:

<virtualType name="MagentoCatalogUiDataProviderProductFormModifierPool"> <arguments> <argument name="modifiers" xsi:type="array"> <item name="advancedInventory" xsi:type="array"> <item name="class" xsi:type="string">MagentoCatalogInventoryUiDataProviderProductFormModifierAdvancedInventory</item> <item name="sortOrder" xsi:type="number">20</item> </item> </argument> </arguments> </virtualType>

Why does the <virtualType> element not have a type attribute? Is it mistakenly omitted? Should the authors of that tutorial used a <type> element instead of a <virtualType> element?