I have a connective tissue disorder that makes my muscles, tendons and ligaments prone to tearing. Eating extra protein won't help, per se, since it's just a bad genetic code for making those structures, but being protein deprived wasn't doing me any favors. Of course it's possible to get enough plant protein, but it's a lot of work and you have to eat about twice the volume of food to get enough. I had major depression and eating at all was difficult, so a big bulky vegan meal was just not happening.

Since eating meat my joints no longer pull apart like taffy at the slightest strain. And I have enough iron to donate blood regularly! The depression is better too, but I've had a lot of therapy and done a lot of work as well, so I can't say if it's related.

I am lucky to live in an area where it's very easy to get all animal products from nice small farms where animals are well cared for and just have "one bad day." It was still very hard at first, I would weep while preparing a chicken for the oven. But I've gotten used to it.