This is a ridiculous comment. Certain ways of behaviour, certain nuances, cannot accurately or reliably be picked up through reading online, only through interactions.
Reading about a topic involving social interaction can definitely serve as a first step to raise awareness of why you're socially awkward. I'm only slightly ashamed to admit that the Good Guy Greg and Good Girl Gina image macros were a source of basic social enlightenment for me. Once your eyes have been opened you can start to improve yourself by paying attention to those interactions when they happen.
"Socially awkward" seems to be a loaded term in your use case. If you are "socially shy", then yes reading would help. But in the case you're not socially awkward in your natural environment (ie you just lived in a different culture), the nuisances are impossible to learn unless you encountered it. Just think of it as a different culture, no East Asian will come to the US without fucking up something small or big a few times, and vice versa. Same for people of different classes.
Why? How can there be such a thing? What is there that prevents someone from recording what they encountered and learned, and passing that knowledge on to others?
I don't think the nuance can be conveyed effectively for many reasons (you don't even know something is nuance when you're used to it). But regardless, remember all the jokes about how someone meets their SO's parents for the first time, preparing to not mess anything up, being told everything that needed to be avoid, and end up doing it all wrong? It's similar to that. You actually need practice.
I don't think anyone's disagreeing with you regarding the need for practice. Reading, Discussion, and Practice are all part of a balanced education, on any topic. I'm objecting to the notion that there are topics for which the written word is useless.
Nuance. Words are not sufficient to convey all things; some things take practice, not knowledge. You cannot learn to play a guitar merely by reading everything there is to know about playing music on a guitar and humans are far more complex than guitars.
But the guitar (or driving, or typing, or ...) practice isn't nuance so much as moving things from (slow) conscious thought to (fast) unconscious processing.
The practice isn't about acquiring information, so much as it's about moving that information to a different internal subsystem.
It is about acquiring information, in the right place, the muscles that can actually handle all the nuance that's too much to think about and do correctly in real-time; people and culture are the same, no amount of reading will make you behave like a native, only time can do that and thus to the point of the thread, you can't learn it until you encounter it and practice a while. Intellectually thinking you know something isn't the same as actually knowing something that takes more than brains. What you know before practicing is wrong; practice is the actual learning and letting go of all the wrong stuff you knew.
At the root of this, you think all knowledge can be encoded in words and shared, and that's the problem, it isn't true. Many things cannot be shared via words, only experienced.
Eh... you do need practice, but if you're willing to sort thru all the crap then reading about things online can be a massive help.
Having things explicitly called out is way more efficient than trying to derive everything yourself (see also, effectiveness of supervised vs unsupervised learning).