It's easier to close the distance than it is to defend it. A boxer would have to be well trained in take-down defense for them to have any chance.
You don't need striking defense when you can easily close the distance in a matter of seconds. Figthers strike more now because of take-down defense, and everybody having trained BJJ. Without those factors, it would still be like UFC I today. These tactics only became relevant because fighters learned how to stay off of, and survive on the ground.
How old are you? You seem to be completely unaware that we had this experiment over, and over again. You sound like a Kung-Fu dork after watching UFC I.
Grapplers almost always dominate strikers who aren't competent in grappling. It's not a matter of anything can happen. It's what's going to happen most of the time that matters. Human error can always cause randomness, but it's not necessarily the average.
Some of you modern MMA fans seem to be oblivious to how this sport started, and why it exists. We have the Internet, and you guys are acting like people in the Dark Ages.