What do you mean by ids are not used anymore?
Loot containers have ids. Not everything is using ids. id is just a property as name is just a property. Some things in the XMLs have ids and some have names.
Here is example loot container from loot.xml:
<lootcontainer id="9" count="0,2" size="6,2" sound_open="UseActions/open_backpack" sound_close="UseActions/close_backpack" open_time="1.5" loot_quality_template="qualBaseTemplate">
<item group="backpacks"/>
</lootcontainer>
(this is from A18 BTW.)