RE:A Bit Confused By This Statement on EXRO Website Presumably you are referring to Level 3 AC charging only? DC charging bypasses the onboard charger and goes directly to the battery via the BMS. So the OBC isn't involved.
Vehicles can AC charge only at the capacity of its onboard charging system. They will limit the input power to what the charger can handle. This likely would also be the case for legacy CD vehicles when faced with AC power sources greater than the CD spec.
High power OBCs are bulky and expensive. Alibaba advertises one online for $9K that weighs 100lb. Putting the engineering considerations aside, it probably would be more cost effective to simply upgrade the CD than provide a separate OBC.
My two cents based on my understanding.