Don't you think transitioning reaffirms gender roles and stereotypes?

No, because transitioning at all requires massive amounts of gender transgression that trans people are often severely punished, or even killed for.

I also don’t think it’s correct to blame societal problems (like sexist gender roles and stereotypes) on individuals. If it’s the individual’s responsibility to dismantle gender roles and stereotypes every single day in the way they dress and interact with society, are you doing it? If not, why do trans people carry a higher burden than you?

This also presupposes that trans people all become gender conforming upon transition, when in fact many trans people are also queer and/or gender nonconforming on top of being trans.

I'm probably missing something, but why isn't being a really effeminate man enough, that there's the need to take hormones and change your pronouns?

I’m a trans man and not a trans woman, but let’s pretend that says butch woman instead of effeminate man. So why couldn’t I be a butch woman? Because I wasn’t one. Seriously, people did not know what sexuality box to put me in before I transitioned. I clearly wasn’t a straight woman (no makeup, a mix of teen boy clothes and some feminine tops) and I was too feminine to be a butch lesbian, but not feminine enough to be a lipstick lesbian. And I don’t say this to mean ‘nobody accepted me in the lesbian community and I had to transition to fix it,’ because I never got any shit from other queer people over it. (And I’m not attracted to women regardless.)

So, socially not transitioning wouldn’t have made me any less gender-confusing to other people. And on the personal level, I needed HRT because periods made me suicidal, all the effects of T make me happy, and it’s my body and I get to do what I want with it. Male pronouns also feel more natural to me than female, so I see no reason to not use them.