Interesting theory, but for me, it's the exact opposite. When I ship my OTP, I cannot tolerate fic that isn't reasonably well done and I'm not willing to read anything just because their names are on it, nor do I think it's acceptable to read fic where the characters could be interchangeable with any other character, in any other verse.

Casual shipping, or accepting a ship, mean I'm not invested in it, like I am with my OTP, therefore I don't care about the quality or plot. If it's good, I'll read it. If not, then no skin off my back. I'll just move on to the next story.

Sorry, but I think this is backwards.