Most tropes have some basis in reality. I've met a few farm-owning parents who view any kind of sentimentality towards animals as counterproductive.

But that's normal - emotionally boding with a farm animal you intend to slaughter and eat is indeed counterproductive.

The trope is about something different - it's about intentionally making a subject bond with an animal over long time, as with a close friend, and then finally making them kill the animal as a final test of loyalty.

Doing that in real life, and for no good reason, is just sick.