As I recall, one of the arguments is that if you are overloading salt, your body sweats excessively to remove and regulate it, then you see a lot of salt on you, so you consume more, etc.
This is just one of many - the catalogs they send are full of arguments of caution on salt intake.
For me, the electrolytes definitely help - yet I also sweat really heavily and seem to need a lot more water than some people get by on. I’m just skeptical about cutting salt dramatically enough to see if that water intake and sweat loss can actually be reduced on a long hot ride. It would certainly be nice to not constantly be worrying about carrying a ton of water up every hill 