Think about the so-called food available to us today.
Imagine you are visiting the zoo, and you see the zoo keepers feeding the animals. They put the food out for the big rhino, buckets of roughly chopped up vegetables, perhaps some pieces of fruit, and all seems well. During a demonstration talk, the keeper offers the rhino a jam doughnut as he cracks some joke about "even this big guy likes a treat each day" and most of the spectators laugh as the rhino eagerly gobbles down the doughnut. A few people would quietly be thinking 'you shouldn't give things like that to an animal, it's cruel' but they don't say anything, they keep their opinions to themselves for fear of appearing to be an extremist.
But now let's say things are different, let's picture a different scenario. Imagine if our rhino is kept in his muddy, grassy enclosure and fed bucket loads of pizza, burgers, chips, pies, pastries, cakes, ice cream, chocolate bars and biscuits. Every day the public visit this zoo and watch the keepers fill our rhino's drinking trough with cola or beer or milkshake, and the ground of his enclosure is littered with chewing gum, pizza crusts, cheese sandwiches and cookies. What would the vast majority of zoo visitors say then?