as i understand it, your views on in-race hydration stem from a two-part thesis:
1. that the human body is wonderfully adaptive to weather and conditions; is great at thermo regulation, and in maintaining great equanimity in the face of harsh conditions; and has an advanced ability to self-meter the need for water and salt based on craving; and that, during races, we ignore our craving instinct at our own peril.
2. when we consider causation: getting the human to this present advanced state is due to evolutionary pressures (and indeed why would it not, since evolutionary pressures are solely responsible for species variation and specialization prior to the advent of farming and animal husbandry).
let's leave part-2 alone for now, because i think that this allows certain folk to segue off, and to hijack the discussion. i don't care how i got to be the organism i now am. i just want to talk about how to comport myself during upcoming races.
i'm 100 percent with you on the folly of hyper-hydration, pre-hydration, and so on. but salt: that's another matter.
simply put, i don't crave salt until it's too late. i crave salt the night following the race, not so much during the race. so unless my cramping is due to something other than electrolyte depletion, i'm blindsided by salt depletion during the race.
why don't we / can't we treat salt the way we treat carbs? we have -- what? -- 2000 kcals floating around in the form of blood glucose and liver/muscle glycogen? so, we have an olympic distance triathlon in us, more or less, but longer than that and we must start taking in carbs at a rate that we absorb carbs (maybe 350 kcal/hr, more or less? that's a reasonable rate of carbohydrate intake?). we don't have to wait until we crave carbs before we start ingesting, true?
why not the same with salt? i don't think i know a successful male pro ironman triathlete who does not supplement fairly significantly with salt (maybe a half-gram an hour or more). why is it folly for me to supplement with salt prior to the onset of salt craving? my own race history argues that it's folly to eschew salt intake until the onset of craving.