Not true, actually. If you're tall, you'll probably fit a stock better, but there are plenty of big mod riders out there. I seem to recall CLS being one of them. It's all about setup, if your mod feels cramped, a longer/higher stem will help.  Interestingly enough, the stem geometry affects the BB rise. This is why mods have massive BB rise, because they need longer/higher stems.  Anyway, if you're cramped on your mod and you don't like the feel of a longer/higher stem, a frame with a longer top tube and higher BB rise will even out the difference.