Ah Warescotfarm, actually the opposite is true
Bear with me (I know it seems strange) but if no one wanted to keep these pigs and raise them for pork there would be no need for the breeders to have litters born. Without these litters being born, there would be no good, young gilts coming through to replace the sow in the breeding herd and if not being bred regularly the sows fertility would drop off and any future litters might be smaller (if the sow was even able to conceive at all).
So, in truth, by keeping and eating the ones who don't make the grade for breeding, people are
actually helping to ensure the continued success of the breed
In the UK 'Essex' isn't a recognised breed of pig - they are known as British Saddlebacks and the breed standard says they should have lop ears. The only one with a white saddle and prick ears that is a pedigree breed in the UK is the Hampshire (but not the original Hampshire breed from the UK, just to confuse things even more