What you are saying is true, but acclimatizing to altitude and diving ascent are two completely different physiologic processes. Going to high altitude means adapting to lower partial pressures of O2 and renal compensation for the metabolic alkalosis that occurs as a result of increased ventilation.

Diving ascent, by contrast is about preventing the sudden precipitation of gas bubbles, analogous to a soda spewing. If you open it slowly, you can release the gas slowly and avoid the spewing that happens when you open it all at once. Same with dissolved nitrogen when you dive. Rising slowly allows the pressures to equilibrate without precipitating.