The vast majority (if not all) of what you learned about cars was done so on your own initiative through your own interest and research, not by building a model kit.
You say that "When you think about it, many of us have learned not just about cars, but how they were/are designed, much of "the how's and why's different types of cars and trucks developed as they did; even a lot about the history of our country in the 20th Century."
But you didn't learn any of that by building models. Building models did not teach you how a car was designed, it did not teach you why cars and trucks were developed as they were, it did not teach you the history of the country in the 20th century. Building a model kit teaches you none of those things. Those things were learned by you via other methods. Based on your age, mostly books until recently, then the internet.
Building a model car may be fun, it may give you pleasure and a sense of satisfaction for a job well done... but it does not teach you the things you listed.