The percentage of alcohol acts as a carrier for flavor. Generally speaking:

This is why most professional whisky tasters add water. A few drops can lower the ABV to a "release point" (often between 35-45%) where the flavor compounds are no longer locked in by the alcohol matrix and become more volatile, releasing their aroma.

In almost every major whisky-producing region—including Scotland, Ireland, and the United States—whisky must be bottled at a (80 proof). If the alcohol content drops below this threshold, it can no longer legally be called whisky and is instead classified as a "spirit drink." Common Alcohol Percentages in Whisky

False. Distillers who release cask-strength whisky fully expect you to add water. In fact, they design the whisky to be diluted by the drinker to their personal preference. Not adding water to a 65% ABV whisky is like eating raw pasta—you’re missing the intended preparation.