It seems like storing obis in the CD tray is very popular. To be really specific, I often see obis tucked between the booklet and the jewel case tabs.
By contrast, things like stickers and registration cards are typically stored inside the booklet, rather than outside.
Now, if I ask myself "what's more common to see, a damaged obi or a damaged registration card," I would definitely say the obi. I've seen tons of obis with tab marks, obis that are folded or torn, etc. By contrast, the registration card is almost always in perfect shape.
That all raises a question for me: why do folks prefer storing their obis outside the booklet, rather than inside? Doesn't that make damage more likely? Is there something I'm missing here?