Emotional support animals are companions that are prescribed by a medical professional in order to help with someone's disability. The most common ones are cats and dogs, they don't take up too much space and they're usually well behaved and perfect for this sort of tasks.
Although, some people went way overboard by picking these huge animals for emotional support, which might be perceived by some of us as ridiculous and unnecessary.
But who are we to judge, it certainly looks unorthodox to us, yet it makes perfect sense to them because that's the only way they manage to get emotional support and doesn't and shouldn't concern us whatsoever.
1. Yep, this is an emotional support duck...on a flight...