I think it's dangerous to set up a dichotomy between "independent thinking" and "groupthink" because individuals learning "by themselves" can also get stuck into a way of seeing a problem that limits the solutions they can access. The "community" working around a certain type of problems (that's true for games, but also for any community of learning and practice) may have some dominant strategies and perspectives, but despite such imperfections it's still better than not having access to others' views on the same problems. To make another anaology (sorry!), if you think of scientific revolutions (as in Kuhn's philosophy of science), the people responsible for paradigm shifts in a field are not total outsiders, they were generally members of the community working in that field.
Perhaps the closest example I can come up with to Civ4 that happened before is classical music. Note, history is not repeated, but is a great teacher, so obviously not all things are the same.
Classical music started as pop music. A certain composer like Bach was the flavor of the month, Ed Sheeran of the period. Fast forward 300 years and you get to the situation we are now in today with Civ4: it's well known, well established, almost everything to be known is known and documented, discussed and discussed some more, to minute details. Largely thanks to this forum. Today, a Bach concert won't fill up a 20.000-seat concert hall. Sheeran will.
In 2023, we have three paths that an interpretation of Bach can take:
One, go into music school, get a hopefully great teacher, learn to read scores, cry trying mastering the organ after spending years on piano, win the classical way. If luck has it and you're talented and willing, you'll become a great Bach player.
Two, grow up on a computer, get into music trackers, start experimenting as a DJ, no formal education at all, stumble on a Bach piece you for some reason like, create a trance remix that makes any classical musicians' eyes pop out.
Three, a combination of the two.
The truth is, there is no "proper way" to play Civilization anymore. It's too well known. I'd as soon watch a game where someone plays with a "purchase techs only" rule than watch someone win "the classical way" on deity. And I guarantee you that it would generate more interest than "yet another deity game". The fact that Civ4 purists "can't get over it" is also nothing new, same happens in classical music. Once "you go crossover", the classical music community pretty much disavows you for life. Because "how dare you".
So, to conclude, keep calm & keep civilizing those squares with communism workshops