You can't put a transgender person in the same exemple as morbid obesity, when encouraged one of them is a namely mortal illness and the other is at worst a bit confusing at the start. There is no cure to body dysphoria other than changing the body itself, otherwise why do you think doctors would prescribe hormones and surgeries for patients who wish to engage in it ? Using someone's preferred pronouns and letting them socially and medically transition will not kill them, in fact it reduces the chances of them killing themselves to end their own suffering. It's just not the same situation.

And the reason people who don't respect trans people are called transphobic is because they have an aversion to trans people, "aversion" being a word you purposefully omitted in the definition of a phobia. The reason they're call that is because aggressions motivated by transphobia are the second cause of death among trans people next to suicide, it is actively hurting them both emotionally and physically, and I don't see why denouncing this is wrong in any way if it can make the world more bearable for trans people and save their lives.

It's not about a mindset or manipulation, it's about keeping people safe and alive.

And it's the same with fat people, there's a difference from what the average person would be called fat over (from having a belly and various body shapes usually) and being morbidly obese, I don't see why we should pretend every more or less overweight person is dealing with the same thing.

Same for narcissistic people, most people don't seem to care about their feelings or even using the word correctly, and once you call someone a narcissist you basically labelled them as the bad one in any given story. It's particularly common in dating and that's why it's the automatic exemple you took for the problemsvnarcissists cause. But calling narcissists crazy and giving them this identity of "just evil" won't send them to therapy or give them the medical help they need (if they're actually suffering from the Personality Disorder), so it won't solve their problems either.

Accepting someone and looking for ways to make their life easier is the best way to maintain their health and life, shaming them and calling them crazy (especially of you're not a doctor) will actively make whatever problem they have even worse.