I'm not sure the intent of that identification chip is DRM. There are several kinds of power adapter (at least 65W and 90W, though I've been told in another comment at https://news.ycombinator.com/item?id=23292819 that there's also 130W, 180W and 230W), all using the same plug; that identification chip allows the embedded controller to know how much power it is guaranteed to get from the power supply, and if it's enough to charge the battery.
It’s more than working vs not working. The power management on the laptop will presumably adjust its charging speed to avoid overloading the power supply.
