Well, there's a lot of differences about Boxing and MMA, and most of them come through in the rule set. That said, I wouldn't quite say that MMA is anything more than stylized violence.
MMA is over too quickly for it to be about anything other than stylized violence.
There's actually a lot of skill and training that goes into it and I think the pedigree of styles that become dominant baselines reflect that. If we look at the history of the UFC for example, pretty early on it was basically a way for the Gracies to show off BJJ. One of the things that become apparent though, was that people that came from combat sports, such as boxing, muay thai, judo, olympic wrestling, etc. did much, much better than people that came from traditional martial arts kung fu, wing-chung, tae kwon do, etc. A large reason for that is that in traditional martial arts, many competitions are light contact and points based, while combat sports involved actual fighting. Continuous and sustained. You had people that weren't afraid of getting hurt and weren't afraid of hurting other people. That's why, as far as traditional martial arts are concerned, Kyokushin Karate and Judo actually did relatively well in MMA, because when it comes to competing, people didn't fuck around.
There's a step further in all of this though. Because people in combat sports are training to win, they don't have time to entertain techniques and theories that aren't proven to work. So while a certain kick might do you well in a point base system because it's quick and flexible, if it has flaws, like for example it doesn't actually hurt or it leaves you easily open for counters, it's not going to be adopted by people in combat sports. What that eventually evolves to is combat styles develop better and more effective techniques for actual combat than traditional martial arts because fighters learn the hard way over and over what does and doesn't work and they have to drop what doesn't work.
This also leads into rule sets. For example, if you have rules that don't allow blows to the head (look at competitive tae kwon do for example) you're gonna have people that don't know how to properly guard their head. Conversely, if you have rules that do allow blows to the head but no blows below the waist, you're gonna develop a defensive style that favors that. You're leg stance is gonna be set up in such a way that makes you more mobile but all of the sudden if you're in an MMA setting you're vulnerable to having your legs being kicked out from under you or easily being sweeped by a tackle. Similarly, boxers can bob and weave all they want, but in an MMA setting, if they pull that shit, they're begging to get kneed in the head.
Which leads me to this . . .
Which is why every ten-fifteen years we need to have the hot shit in not-boxing get annihilated by whatever boxer will do it for the least money.
Every time you train for a certain rule set, you're gonna be competent in that rule set. If a career MMA person steps into the boxing ring with a career boxer, they're at an extreme disadvantage. That boxer has a decade plus years of experience in strickly boxing, where the MMA fighter doesn't. Their fighting style has been catered to match the rules and min-max the fuck out of them for their advantage. The MMA fighter on the other hand doesn't have the same experience with rules or styles.
Even when rules are similar but enough has changed, there will be a disadvantaged fighter. Somewhere out there is a video of an exhibition match between an American Kick Boxer named Rick Roufous and a Thai Fighter named Changpuek Kiatsongrit. American Kick Boxing didn't allow leg kicks. Thai Boxing did. Rick Roufous did not know how to intelligently defend against leg kicks, to the point where his opponent won by TKO because he basically destroyed the fuck out of Roufous' legs. In an exhibition match, a champion kick boxer lost to a thai fighter because the rules did not favor him.
There are similar vidoes out there of boxers losing to thai fighters for the same reason, BJJ wrestlers losing to Judoka when it comes to stand up game and Judoka losing to BJJ wrestlers when it comes to ground game, and on and on and on. While not necessarily recorded, you'll hear similar stories pre UFC days. MMA isn't actually something new. Cross style exhibition matches are part of the game and are often used as both marketing opportunities as well as good will events between different nations and cultures. The guys behind the UFC though? They just figured out how to really capitalize on shit and the ball has been rolling ever since.
Also, it goes without saying, what your dad's friend did was pretty stupid, but I think we both already knew that. :)