I think massive CHAdeMO plugs might have been for ultra rapid charging that never rolled out. There are brochures of 350kW+ watercooled CHAdeMO charging test equipment floating online, noted as plug limited to 200kW, dated at least as far back as 2015. That was when Tesla was still rolling out V2 150kW. So the plug overall dimensions and pin sizes are probably way overspecced for what it is in practice.