On the surface, it almost sounds like and intelligent statement. You might think why wouldn't that be more or less true. And in some cases it could be.
But you might want to compare it to say, if Clark Garble, and May West had a child together, wouldn't that be the same as half of each parent? Well, it would actually, but the genetics of the child might recombinate in a number of different manners. Giving you something different from the parents. Some traits maybe there but accented, or declined, or changed, or rearranged into something else. Or you simply don't finish what you've started.
It might be something good or bad, that's why you might get lucky, or you might breed for a long time and not really care for your results.
A lot of breeders will immediatly stop when they hit something that looks inferior. And go off in another direction. The problem with this type of breeding is recessive genes. A line of whatever measure, can be set up to crap the next generation. Or the reverse, you might have grown some females, that weren't that good. But the inbreeding, to the next generation, show them to be terrific.
One of the main causes of this is "instability" meaning genetic integrity is fluid at different points before and if it becomes stable.
And one of the main causes of instability is. The type of breeding, where you drop what your doing at the first sign of decline and run off to something else.
My experience tells me that a hybridized strain for the most part doesn't really become stable until you reach about f12. Most people aren't even going to get there probably, to even see if they are totally succesfull.