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I see your point that an IVF clinic could choose to only extract or fertilize a few eggs from a woman who produced an unexpectedly large number. And most clinics whose policies I'm familiar with do offer patients the option of not fertilizing all the eggs that are retrieved. However, it's not an option that most patients are going to be interested in, when they're facing the huge cost of these procedures. They want to maximize their chances of having a baby.

If a woman produces say 20 eggs (and it makes no sense not to extract them all, since the quality/maturity of the various eggs can't be reliably determined until after they've been extracted and studied under a microscope), and chooses to have fertilization attempted on only 5, there's a very large chance she won't get a baby at all. And after she's thrown away 15 eggs that cost $10,000+ to get, and still has no baby, she's going to be wishing that she had had those eggs fertilized, and frozen however many extras were successfully fertilized, because then it would cost relatively little to go through the embryo transfer portion of the cycle again. Instead she's faced with starting over and trying to produce eggs again, but she may not have another $10,000, and by the time she saves up that much, she'll be older and have a smaller chance of success.

And many couples want to produce as many embryos as possible in one ovarian stimulation cycle, because they'd like to have more than one child. If they have extra embryos left over after having one, they expect to use them to try for another child, without incurring massive expense again.

Within the next few years, egg freezing is likely to become a reliable technology, and at that point, it will make sense for couples who have ethical issues with discarding embryos, to freeze extra eggs, and fertilize them later only if more embryos are needed. Right now, however, only a very small percentage of eggs survive freezing and thawing, and the rates are especially low in older women. It is an approach that is recommended only in case of young women who are undergoing cancer therapy which is likely to destroy their fertility, and who do not yet have a partner. There is a new company (Extend Fertility) that is pushing egg-freezing as a way to "buy time" to find a partner and have a baby, but the reputable doctors and professional associations in this field have denounced this practice as unethical given current technological limitations, since its unreliability means the company is selling false hope in most cases.

It's been a pleasure discussing this with you. Unlike most people who hold your view on the status of fertilized eggs/early embryos, you are genuinely interested in facts. It's quite refreshing!