Um..I'm confused.
Why would a book having OGC affect your HOME game unless you were a publisher?
Personally, I stand by my belief that if WOTC had DDI running in 3.x, they could've even made EVERY book they produced OGL and STILL killed off the vast majority of the 3pp market.
You know, this came up for me first because I ended up allowing options into my home game. And then, to make things easier for my players, I began to consider how I could make those options available to them. Could I, for example, make a campaign web page with optional rules posted? Could I share them with others? Could I use an online database to allow players in other parts of the world to partake in my game?
If they were OGC, I could do that without having any shadow of a problem. If not, well, not.
I found myself in a quandry between using the best rules I could, OGC or not, and limiting the scope of how I used them, or using the best OGC rules I could, allowing me to throw the scope wide open.
And, suddenly, it became obvious to me just how inclusive the OGL could be, and publishers who provided plenty of OGC were. They were helping me make my game my own, and helping me share it with others. OGC says "This game is yours" while closed content says "But this is ours". I discovered that I value the former.
And now I am working on a free ruleset that I can share, which will be well over 90% OGC, which can be used by other GMs to tinker with other rulesets, or run as-is, or whatever they like.
Because I value that, and I want the scope, and I want to contribute.
RC
EDIT: Oh, and Dire Bare, the Section 15 will show you where OGC was taken from. Many publishers have built on, and modified, each other's work. That is a good thing, and has led to some great products!