At least a couple of distilleries I visited in KY recommended trying bourbon neat, with a drop or splash of water, and on the rocks. Each variant gives a slightly different expression of the spirit. So that’s at least an “official” warrant for the idea that it’s not ruining the whiskey. The same goes for scotch. Some whiskeys are just more interesting when diluted a bit. (And, in fact, I think the youngest Laphroaig used to contain a suggestion on the bottle that it should be consumed in a 50/50 ratio so as not to overwhelm the palate with peat smoke.)
I find the “whiskey should only be consumed neat” crowd to have the same gatekeeping mindset as the “coffee should only be drunk black” crowd. If that’s how you like it, great, but it’s not a general rule for how these libations ought to be consumed, much less a marker of how “hardcore” you are as a drinker of them.
I'm not sure this is universally true. When I've visited Scotch distilleries, the person leading the tasting would suggest you first try it neat, then with a few drops of water. Particularly when drinking cask-strength whisky (50%+) it is typical to add some water to mellow it a bit.
On the rocks is somewhat different, as it will dilute the whisky progressively as it melts, until it's lost most of its flavor. Chilling the whisky also reduces our ability to taste it, as our tongue is less sensitive when cold.
(If you're interested in the science of how dilution and temperature affect our experience of drinks, I highly recommend Dave Arnold's book Liquid Intelligence).
I've never visited a Scotch distillery, but I had the same experience at the KY Bourbon distilleries. I found that I liked it best in the middle: with a drop of water to smooth out the alcohol and open up the flavor profile.
Same with coffee, actually: a little milk to bring out the flavor, in all but the most dry and winey specialty light roasts. From what I remember, the milk actually binds with certain chemicals in the coffee, allowing other flavors to come through. I believe this is also why even a small amount of milk makes coffee significantly easier on my stomach than completely black.
I've visited Scotch disilleries and they will all tell you to enjoy Scotch however you like, and that adding water can indeed open up the flavor and aroma. They encouraged you to try it! One person did caution about putting ice in your spirits since very cold liquids could numb or mute your tastebud sensitivity a bit.
With coffee it's also a thing of covering defects, milk is amazing in it's ability to mask bitterness and take away from the harshness, sugar's great for very acidic brews.
I love my specialty filter coffee but I often get gifted pretty dark and rather cheap blends, which work just fine for a milk coffee drink or other combinations
We visited Highland Park on Orkney (highly recommend) and the guy giving the tour insisted that putting a few drops of water in your glass is the way to go. The science is a bit murky and I haven't found any blind taste test results that could guide me to the proper amount.
With Scotch prices what they are I switched to Bourbon and actually a really cheap brand (Benchmark) and when I don't drink it on the rocks I mix it with diet ginger ale: that really "opens up" something but I don't know what it is.
Speaking of cheap, i discovered the E&J XO brandy a couple years ago and it blew me away. It's only about $12 where i get it and it beats the crap out if the $40 specialty brandy's I've gotten over the years. I have the suspicion that they flavor it or something but it's full proof and doesn't say it's flavored anywhere. It's honestly so good it feels too good to be true.
I find the “whiskey should only be consumed neat” crowd to have the same gatekeeping mindset as the “coffee should only be drunk black” crowd. If that’s how you like it, great, but it’s not a general rule for how these libations ought to be consumed, much less a marker of how “hardcore” you are as a drinker of them.