Afaik it's a misconception that MRT necessarily involves the destruction of an embryo. The spindle transfer method transplants the mother's egg's DNA into the donor's egg before fertilization, so only one embryo is ever created. The UK trials exclusively used the older pronuclear transfer method, where two embryos are created and the donor's is destroyed, because the journey to full regulatory approval took about a decade and embryos are currently safer to freeze and thaw than eggs. In a hypothetical scenario where MRT became as widely available as IVF, this would not need to be the case for new patients.