"Everything works the way you want it to work."
Shout out to the Dungeons and GURPS channel, a great one to follow with a lot of "open thought" about the game, combat, and other aspects of the games. Lots of great discussion here, including a comment about "kitchen sink" settings being looked down upon in different communities. He mentions mixing things from several games and editions of D&D, and even Pathfinder, into his own campaign world, and it just all works.
He loves his "kitchen sink" campaign world.
That statement reminds me of the old days, and this is exactly what we did. Mystara was this cool mixing pot of everything, D&D modules, AD&D modules, and all sorts of crazy things. We didn't need "world support" for a game world since we just pulled in anything and everything cool into our world.
And no one told us we were doing it the wrong way, because nobody had ever done this before! What "wrong way?"
For all we knew, what we did back then was the "right way," and everything past 1990 with game worlds and dedicated module support per product line was doing it the "wrong way."
Maybe we have been playing D&D wrong for the past 30 years and everyone forgot this.
Maybe AD&D 2nd Edition was the beginning of the end, and the birth of this terrible corporate era we live in, where you have to associate a product you pay companies money for as a lifestyle and you are expected to attack anyone who thinks different than you.
But, you can't take Pathfinder's iconic characters and make them - NPCs - in your homebrew world! And put them alongside your favorite characters from Forgotten Realms novels? No, you must be breaking some rule somewhere! And the irony is people would tell you that you are breaking the game or somehow your creation is less than the official worlds and products.
What you have fun with is always the best.
Kitchen sink away.
I swear once you escape the gravitational pull of what's popular you get a lot of wonderful free thinkers, rules hackers, system tweakers, world builders, and just the most original and "do what cha want" crowd of interesting roleplayers.
I feel like I am in this wonderful crowd of hippies and counter-culture types, and we are all sharing ideas and thoughts where everyone can be right, everyone has great input, and you can be yourself and tweak rules and systems all you want to build the game in your dreams.
Instead of being forced to fit your big dreams in a company's tiny and structured box.