Chief is just as experienced as any of those. Since he was six years old he's done nothing but fight. He has more combat experience than a clone that experiences childhood at an accelerated rate, or a Jedi who is a keeper of the peace and has seen very little battle. If Chief hadn't relieved the Librarian's gift, he would have been composed. Without Cortana to distract the Didact, he would have been torn to pieces. I guess you didn't watch the cutscenes as well as you thought. Also, saying "anyone as capable as the chief" doesn't include a lot of people. Maybe one or two clones, the strongest Jedi and Sith, a few bounty hunters.

Any jedi is more capable (MC cant use the force!) MC is between 16-19 hes been fighting since age 6? Thats 10-13 years. Clone wars was 18-25 years long; any vet has MORE combat experience. Obi, mace, lumi, barris, ahsoka, shaak ti, aayla, plo kloon, ki adi mundi, and MANY more fought plenty of battles. Yea MC had help and a team. A force wielder skilled enough doesnt need a diversion to fight a forerunner. (Yea the item the librarian gave MC is needed or something like it is needed in MC or non force wielder case, not impossible for them to obtain them) Your basically saying "only MC's team coulda killed diadak." Guess what; you DONT need snake an his team to take out metal gear; you dont need a crysis squad to take out those crazy a55 aliens in that game; there are plenty of ways around things. Everything has weaknesses and guess what; "On a long enough time line the survival rate for EVERYONE drops to zero"--->tyler d

The Jedi got killed by the clones, who can't use the force. Chief isn't a teenager during Halo 4. You clearly know too little about the lore to be even having this discussion. Any Jedi or Sith would be composed, because there's no way the librarian would help them to kill her.

Wrong, during the halo trilogy the Master Chief is 39. Not counting time spent in cryo.

The jedi got shot in the back by a cadre they had been fighting with for 20 years ish. ANY ONE can be taken off guard. The librarian had the key item to diadak's defeat yea, That means THERE IS a way to beat them. You dont necessarily need the item itself, just to be able to do the same effect as the item does.

The chief didn't need the Librarian's gift to kill the Didact. He used a nuke to kill the Didact. (Also, by the way, there is speculation that the Didact may not even be dead, as he voices over the end cutscene of the game.) He needed the Librarian's gift no not be composed. I'm not sure you're paying attention to what's being said.