Another reason is that you might have a 2 plugin household. When "solo charging", 80 (100) is lovely but when "team charging" you may want to throttle it back so a same-circuit 14-50R can run on another vehicle.
Just a note about this: you really want to use separate circuits where possible, even if you have 2 14-50's and you *know* that you'll never use them at the same time. You can take shortcuts and put 2 14-50's on the same circuit, but you have to mark them and make sure they're not used at the same time. Any HPWC installed on the same circuit as a 14-50 must be configured for 50A (40A continuous load) or less only.