Question: I asked <https://stackoverflow.com/q/14541047/1888017> and for some reason it's closed. I can't figure out why. I read the FAQ several times, and I know that it is possible to make a concrete answer, because it's just about differences between protocols and their performance.

And it's also not broad, like how to build a rocket or a million-dollar business.

So please explain to me what's wrong with it.

Answer: 
It's impossibly broad. A person could write a book attempting to give a comprehensive answer to the several questions you pose. The FAQ specifically states that 'it would take a book' is too broad.
It's enormously wide. It's a great example of a question that could be answered by a book. Consider asking which is supported by more platforms/libraries/programming languages (pick ONE) or which is fastest for a particular kind of use (be detailed) or which is easiest to learn, or easiest to hire developers who already know, or easiest to debug, or capable of handling your particular payload (large, or oddly formatted, or whatever) or most secure, or ....

ONE question. Not "tell me about the differences". It would be like asking whether I should live in Canada or Europe. Unanswerable in general, and you've provided no details to take it away from the general.