Yerba mate is a slightly different plant evolution that produces roughly the identical neurotransmitter imposter so it hits slightly different because it gets into parts of the brain the other one doesn't. It's not enough to become the standard because the other one from c3 cephids are better.

1.2 billion years ago you were a flatworm in the lush tropics of Africa crawling through the mud trying to get on land. You typically got the immune system of other more highly evolved animals sprayed into your face. This other immune system fluid that got sprayed on you contained molecular C31b attack membrane complexes [ https://www.youtube.com/watch?v=LmpuerlbJu0 ] that would put your system out-of-balance, when this out-of-balance is detected, it means we're under attack and it's emergency kill or be killed time. This is where "fight or flight" comes from inside you. Over the millions of years this dynamic walked in to be between plants and herbivores who used it to create a symbiotic relationship, you spread caffeine seeds, with gusto, and I'll give you a hit of your own fight or flight "Super-Sayan 3 - Ascended" that keeps you alive in the fighting pit.

Youtube Video: "The greatest addiction Ever" by CGP Grey
https://www.youtube.com/watch?v=OTVE5iPMKLg