It activates the same chemicals in your brain as cocaine! 
Well, yeah, there are only ~~three~~^[@Neuromancer49@midwest.social corrected me] a few neurotransmitters. That's not saying much.
You know what else activates those chemicals? Practically everything. When scientists breed "knockout" mice without dopamine, the mice just stand there until they die of thirst, because there is no reward for.... living.
It contains more germs than a toilet seat! 
Germs like moist surfaces. We don't want germs on our toilets, which is why we make them out of porcelain, which is hard, dry, non-porous, and easy to clean.
If it had more germs than your colon, then I would be concerned.
Dopamine does a lot in the brain. Much of its function depends on where it's active. When released in the ventral tegmental area, it causes reward and happiness. In the basal ganglia, dopamine helps us coordinate movement.
Since I'm already on my soapbox, I'd like to point out there's more than 3 neurotransmitters. These are the basic ones:
https://en.wikipedia.org/wiki/Neurotransmitter?wprov=sfla1
obviously. But for the people who don't know this, unlike me, maybe you could explainm this one
Sorry, that was maybe too pithy for a science post. https://www.smbc-comics.com/?id=3339
no, it's fine, as I am a scholar. But I am also a communist, and as such I think of the poor and uneducated a lot. I think your comic will help them. Not me though, I knew this.
Breastfeeding babies. Moms get a happy hormone from it.
direct from wikipedia
I didn't know hormones and neurotransmitters overlapped like that; I always separated them in my head. TIL.
Why do I frequently see the neurotransmitters narrowed down to dopamine, norepinephrine, and serotonin? Are they the most important ones?
That's a surprising statement to me. Honestly, those aren't even the most important. Glutamate is the most common neurotransmitter in the brain. But dopamine, norepinephrine, and serotonin are responsible for some very "classic" bodily functions like reward, adrenaline, and sleep.
Now, hormones are typically separate from the brain - there's a barrier between neurons and your circulating blood maintained by astrocytes. This is the so-called blood-brain barrier. I do not know if there are examples of Oxytocin and Epinephrine crossing the BBB, as I did not study it. https://en.wikipedia.org/wiki/Blood%E2%80%93brain_barrier?wprov=sfla1
I'm not sure where I mislearned that then.
War crimes keep my brain healthy?
Ducking autocorrect strikes again. Astrocytes
Although I've never thought much about it I would think that neuropeptides that are produced in the brain would likely have local activity. Orexin is an endogenous neuropeptide that can be administered in an inhaled form with a very potent effect. I listened to a talk on it once and apparently you can be going on 20+ hours awake and barely able to keep your eyes open to immediately awake like you slept for 12 hours. He said that the air force uses it for B-2 pilots and other extremely long range missions.
This explains the irresistibleness of gabagool.