You know what I think, lol...as to why we are kit/mix-it-up scrappers. CT's. I started digi scrapping and CT'ing when you were required to use ONLY the kit you were given. If you HAD to have something that wasn't in the kit, you could pull from other kits by the same designer, but it was encouraged to only do so if it was absolutely necessary.
Things have changed. Designers require anywhere from 75-90% their products, because they realize that they realistically can't give their CT's everything they need in one kit - and sometimes some other designers can create something that another can't (for example - tears/folds/overlays, etc). So there is a bit more flexibility in choosing what you'd like to use on your layouts for your CT's (depending on who you CT for). Site CT's are even better because many allow you to use anything from the store, mix it up, you don't have to go 100% any one designer (again, dependant on WHO you CT for, lol).
Now that I'm not on any active CT's, I feel total freedom to do what I want, lol. I love it! I'm back to scrapping for myself - and it allows me to use anything that speaks to me and my layout...instead of scrapping a layout with the designer in mind.