It's not unusual to hear chefs protest 'well done' steaks, and some restaurants won't even honor the request, but instead of just calling you stupid, this chef broke it down in a reasonable fashion.
Funny enough, the explanation came in the comments section of this hilarious Hank Hill meme on Reddit:
Chef Geoff said he has run a restaurant for over 20 years and went pretty in-depth with his explanation, but the TL;DR version was that:
"High quality steak cuts aren't the right meat for doing well done in the same vein that Ahi Tuna shouldn't be cooked well done."
Comparing it to Ahi Tuna, Chef Geoff said, "You can buy Ahi Tuna at $30.00/lb, so why would you cook it so that you couldn't really tell the difference between that and the tinned stuff."
He then went on to say that different cuts of meat are meant to be cooked differently, from boiling, to microwaving, but steak is ultimately have less doneness.
Aside from Chef Geoff's argument, studies have actually linked well-done steaks to Alzheimer's disease because the blackening produces something called glycotoxins, which has been known to increase symptoms of dementia.
Hopefully this helps your argument as you try to explain to your loved ones what good meat's supposed to taste like, but there will always be difference in opinion. All you can do is hope and pray that they'll change their mind someday.
If that doesn't persuade you to try a nice medium rare steak, just know that Donald Trump likes well-done steak: