First, It is not. Your bias for MMA makes you think that. Second, MMA fans get defensive and start to approach the argument from a "soccer vs mma" stance.
The argument is not "soccer >>> mma." The argument is a relative one. Meaning, if a professional soccer player can play for 85 minutes, and still have the energy to explode one last time in the last 5 minutes, to score the game winning goal, likewise, a professional mma fighter should be able to find that last burst of energy and finish his opponent in the final minutes of the fight.
Don't think about it from a "soccer vs mma" perspective. Think about it this way, if you hire a plumber, you should expect him to live up to a high standard for his profession, and if you hire a surgeon, you should expect him to live up to high standard for his profession.
You can't say "well, it is ok for the surgeon to not be competent at his job because surgery is much harder than plumbing." That is some bullshit way of thinking.
If surgery is too hard for a person to perform at a high standard, then maybe he/she shouldn't be a surgeon, because there are high quality surgeons. It can be done.
We have seen mma fighters that can perform at a high level through 5 rounds (even at altitude), so the excuse of "mma is much harder" is utter bullshit.
The argument for my "mma is much harder" excuse is strictly based on two things:
- team sport vs one man sport;
- the number of breaks;
I've played some and I have watched a lot of soccer in the past. Also, I have watched rugby.
The thing with soccer is that there are a lot of moments when the players do nothing.
- faults or injuries;
- offsides;
- arguing with the referee (happens all the time);
- corners;
As a defender, you benefit breaks when watch how your team is doing on an attack.
As a striker, same when the other team is attacking.
Sure, you must pay attention to your position and to your opponents, but it is kind of break, whatsoever.
In mma, you don't have this. Except fights like Woodley vs Maia, there can be 5 minutes of no breaks, of punches and kicks and takedowns.
I agree with the "surgeon/plumber" argument.
Your main argument is that "The fighters of today can't do it because they are not life long MMA athletes. They failed in popular sports, Started wrestling, and then ended up in MMA. That is the basic path of a current UFC fighter."
I am not sure I understand it fully. DC, for example, didn't fail in a popular sport.
Conor, for example, is a striker in MMA. He doesn't try to wrestle. Very rarely, he tries a kick. He uses his boxing in his MMA fights. And still he gased against Nate. I don't see professional top boxers gasing that way after two rounds.
I hope you are right with "Why will future MMA fighters be able to go 5 rounds? Because they will start at a younger age. If you learn to fight hard for 1 round when you are 15 years old. "