Instead of falsely spouting off about fallacies, why don't you actually read the rules. The rules do in fact cover non-combat options for all stats. Not just charisma.
The rules do offer ways to specialize. Bards and rogues get to have greater bonuses for skills than other classes. You can use either class to specialize or build a primarily social character.
Why would you need rules for something that takes a few seconds to just do?
Again, I don't want a book to be telling me how I should play my barbarian PC.
No it doesn't. The rules provide me with ways to specialize in gambling. All I have to do is choose the gambler background, which the rules allow me to take. Then I give myself tool proficiency gambling items(dice, cards, etc.) and then I ask the DM to allow you proficiency with gambling(wis), which the DM will allow since it's a very reasonable request and the rules allow the DM to add in that skill. Viola! A professional gambler who specializes in gambling created via the rules.
If you take a moment to understand the rules, instead of engaging tunnel vision, you will see that they are more robust than you are claiming.
Try reading the PHB. It will help you understand how to go about learning something after you are born. Backgrounds which are not tied to class allow you to learn proficiencies of your choice, as does the skilled feat.
I've played D&D without them, It's a bit more work to do the random stuff without dice, but not terribly difficult as it can be done fairly without any physical items at all.
Again, just because you claim shortcomings, doesn't mean those shortcomings exist, either. So far you've made claims that the game is mostly combat, which I refuted using the rules, claimed that only charisma is for non-combat, which I refuted using the rules, and claimed that you can't specialize or create a professional gambler, which I refuted using the rules.
You don't need to be a noble to build a castle. D&D is not the real world. And you don't need a book to give you an answer to that. The DM can answer all of those questions very simply. It's not the Oberoni Fallacy to say that, either, as it's not a problem for the DM to have to actually come up with stuff for the game, but rather a strength. I'm not forced to fight a system if I want castles and a feudal society to be different than the One True Way the book would say that those things happen.