People like to see themselves in a good light. Therefore it makes sense to try and find someone else that suits your image of right.

It's possibly the hardest thing for most people to do, to face their own problems and bad sides. They'd have to make themselves feel bad, feel down, accept that they're not as great as they imagined to be. Even if that is the only way you could become a better person. You cannot fix the problem if you refuse to find out what it is. But hey, it's so much easier to direct attention outwards. Find someone else to fit your worldview and if something goes wrong, you can always blame them for it. (add suitable smileyface)

Food for thought. Hope it answers your question.

What you are describing here is known as "face culture". It's in the blood of the East Asians to "save face" and to "keep face". When you are challenging your Chinese friends to a debate, you are, in principle, challenging them to a fight. If they would partake, someone would "lose face", which is a serious thing. You could somewhat compare it to being humiliated in public. If they don't take a strong stand for something, it's just that they don't want to "lose face" or make anyone else "lose face" therefor performing the glorious and highly esteemed act of "save face".

Especially the Chinese people have a zillion tacit rules to follow regarding the "face". Certain people are, in principle, more valuable than others, you should always try to "save face" of the other person in your group and never challenge it. Then there's not only the face of an individual. As you may know, Chinese culture is more collective than individualistic. Traditionally, anyway. There's also the collective "face", like "face" of your family, "face" of your workplace, "face" of your nation etc. You have to study this issue a really long time to fully understand all the rules and nuances. Not even the Chinese born Chinese people can really explain the "face culture". "It just is like this because ... it is like this." That's because it's largely tacit knowledge. You just have to 'get it' through experience.

It helps to get along with people, sure. It also forces people to do many things, including the wrong thing, knowingly, because of "saving face". Even if the end result is 100% certainly going to be a horrible disaster. 

To give more perspective... you can roughly compare East Asian "face culture" to the Arabic "honor culture" or the more western "culture of shame".

It seems to me that your example is like a competition between an extrovert and an introvert. 

Basically both A and B in your example can be fluent. It's just that B has not given evidence of this, while A is shooting it up like a machine gun. If we follow the dictionary here, A seems more fluent (=able to speak smoothly/easily/readily). However, again, we cannot be sure due to lack of evidence from B.

I've heard some people explain fluency like this:

"You're fluent when you can joke in that language."

"You're fluent when you think and dream in that language."

...and there are surely as many interpretations of this as there are people. 

I think that you should be able to understand and produce the language with a good flow and then you are fluent. Eating a dictionary is not obligatory.

People like fast food. People also like quick achievements and feeling good about themselves without too much effort. That is the reason, I gather. Anyone can answer "What's your favorite ___?" or "What is your least favorite ___?" and it serves as a slight ego massage on the side. 

People don't seem to want to discuss any too serious issues, either, and definitely not philosophy or science of any kind. There's a big effort to partake and a big risk at making a fool out of yourself. Well, that's my experience anyway. 

Maybe the youth of many users is largely related?

You just have to push on with the studies and use the language more. 

Do you know this saying?: "You can only be as good as your teacher."

Perhaps you're experiencing this problem. If you're always studying from the same sources in the same way, you will eventually learn as much as these sources can teach you. If you continue to study from where you've already learned everything, you'll simply get stuck with the same end result. Also, Friends isn't necessarily very high quality English (sorry friends of Friends). 

Take up a wider variety of subjects and sources to learn from. Read, write, listen, speak. Many people read and listen comfortably, but have more anxiety with writing and speaking. Also, if you live in your native (language) country, your English will very easily be corrupted by the patterns in the language spoken/written all around you. It requires extra sharpness to avoid that. On the bright side, everybody makes mistakes. Including the native speakers. With experience, you simply do less mistakes. 

@Susan

Yes, Finland. International campus, though. Mostly Europeans and East Asians, a handful of Africans and Americans. 

People generally don't appreciate if common routines are broken somehow. After all, routines give safety, comfort ("I know how this thing goes."). Also, the expressing of negative or positive emotions is definitely culture related. In the traditional Finnish way, it's actually worse to express positive emotions and more appropriate to express negative ones or humble ones in a slightly negative, perhaps self demeaning tone. Nobody wants to listen to a long, dark and heavy story, though. Unless it's on a proper metal album.

It's very true that the Northerners traditionally restrict, or choke, expressing emotions. It's kind of seen as revealing your weakness or being a drama queen, making number of yourself etc. Withholding 'unnecessary emotions', again, is acting civil etc. Rough nature, Protestant Lutheran ideas... South European people are much more emotional. For example, I've made an adult Italian restaurant owner cry in public by refusing to sit on the table he offered. The only table in the scorching sun and many tables free in the shade. That was a weird experience. Anyway, in many respects they are more openly emotional in South Europe. Also, in East Europe.

I've done some research on the people's emotional openness and emotional response during the last few years.

I wonder if there is an American at all, beyond the surface.