I agree with the intention but not the solution. Severe dehydration is a medical emergency.
Powder doesnt do anything for dehydration without water, and water that is completely safe for an international traveler to drink isnt universally available. Water with local microbes and contaminants is available wherever people live.
Given a choice between untreated groundwater and beer, I’d choose beer.
So for emergency preparedness I’d rather carry a personal water filter and salt tablets. Once out of trouble I’d be eyeful for months and try to find a doctor who was familiar with local waterborn diseases of that region.
The other electrolytes are less likely to be rapidly/severely depleted unless you’re a professional athlete or running a marathon and excessively peeing like an undiagnosed PWD.
Personally I wouldn’t worry as much about what was available in a hospital but dehydration can happen when there isn’t easy access to medical assistance. Given a chance to prepare, I wouldn’t venture into a foreign territory without being able to ask for food and water and say I’m in trouble, please, and thank you in the local dialects.