No, this is not a joke.
Jack Bauer, the hero of 24, is the key agent on the Counter Terrorism Unit. He will torture (mostly just interrogation with yelling and threats), kill, fight his superiors, and lop off heads in order to save the day. He developed a drug addiction to go undercover with a cartel, stopped LA from being nuked about three times, saved the President of the United States at least a dozen times, and will occasionally go on revenge-fueld rampages. He is also the winner of going-the-longest-without-sleep-while-still-kicking-ass award. He's mostly a lone wolf, because everyone who helps him eventually dies.
Harry Potter is essentially experiencing the worst high school experience since Buffy the Vampire Slayer. Instead of being born with martial arts skills and preternatural strength, all he has are the wits of a ten-year-old (to start with) and inborn magical ability that he's still learning to control. His biggest assets are his friends-- one of whom is smarter than he is. And he's got a death sentence on him since he was born, all because of some Saruman wannabe who has his own Manson family.
So, what do the two of them have in common?
The Cassandra effect.
Going through both series, you'll notice that no one actually listens to either Jack Bauer or Harry Potter. If people listened to Jack Bauer in several seasons, the show would be called 12, not 24. Every time Harry Potter falls head first into a plot, like some sort of magical Jessica Fletcher, no one over the age of 18 listens to him. They are both Cassandra, knowing something will happen for certain, only no one will listen to them, especially when they're right. Leaving it up to our heroes to act on their own to save the day, despite the stupidity of others.
Now, granted, it's a plot device specifically designed so it can end with the hero standing alone against all odds, with maybe some cavalry coming over the hill at the last minute. One might say it's a very American concept -- rugged individualism, cowboy duels in the street, the Lone Ranger, every superhero, every Clint Eastwood western-- except that there is still the basic mythology of Odysseus, or Bellerophon, and other folks of yore who have special powers and abilities that make them the only ones to face demons and monsters. It's the same concept, only we need different reasons for the lone hero to be lone anything.
In the case of comic books, that's easy-- most superheroes have superpowers that enable them to go toe-to-toe with the bad guy and walk away. Even Batman and Iron Man have special toys, special training, and a wealth of experience on their side.
But what happens outside of that? When everyone has the same training? The same knowledge base?
Enter the Cassandra effect. In both cases, it stems from Finn's Law of Committees: to get the IQ of a committee, you take the total IQ of the individual committee members, and then divide it by TWICE the number of members on said committee. Why? Because people are dumber in groups.
In either case, this holds. In the Hogwarts School model, the faculty obviously know more than this pissant little child, so how could he possibly have the answer to anything in particular? In the case of Jack Bauer, the CTU bureaucracy looks something like the bureaucracy of the damned, filled with political operatives who know nothing about kicking ass and taking names, and everything about kissing ass and shuffling papers. And, in both cases, our heroes can only appeal to an individual --Harry Potter's Dumbledore, or Bauer's President Palmer -- and that person can cut through the red tape that has made everything so very, very screwed up.
If you don't have that, you don't have a plot in either case.
"Oh, Harry? People are going to try and steal this valuable stone we have in the forbidden wing? We'll triple the guard on it. Thank you."
"Jack, you've got information that says that there were other people behind the terrorist threat? Sure, we'll have an air strike on them in the next five minutes."
Sounds boring, doesn't it?
At the end of the day, individuals who will fight the good fight are always more appealing to us than a massive, faceless bureaucracy. We trust individuals to get things done, but not the byzantine structure of bureaucracies, who will seemingly let anyone in. It doesn't matter if it's the IRS, the State Department, the NSA, CTU, or Hogwarts. But good fiction uses this plot device well, exaggerating the natural ineptitude of bureaucracies into a plot point -- and sometimes, you don't need that much exaggeration.
Even when you have something like the Magnificent Seven, or the Avengers, it's very much the same concept. It's the individuals coming together to take on a threat that none of them could deal with alone.
Now, one could counter with military fiction... except in that case, fiction makes certain to focus on the officers and high-ranking foot soldiers -- people who have already been promoted because they have special abilities and knowledge that put them at the head of the back. Just look at 300-- we focus on, possibly, six of three hundred Spartans. It's hard to make us emotionally invested in 300 individual soldiers in the time and space allotted, but making us invested in a select few allows us to be invested in all of them.
At the end of the day, we the audience become invested in individuals. The Cassandra effect -- or the committee effect -- gives writers the excuse to focus on a select few in a modern age where great big monolithic installations are supposed to take care of everything.