Debate
Yes, this is a debate forum. In that spirit...
"you would know that we have teeth, esophagus, stomachs, intestines, liver etc for a reason."
I agree entirely. We do have teeth, esophagus, stomaches, intestines, and liver for a reason. However, that reason doesn't necessarily have to be because we NEED food, but only because those structures are designed to process food.
With that said, I've been experimenting with fasting for a long time. I can tell you that breatharianism (regardless of whether it is true) is something that most people on this planet will not be achieving any time soon. If someone thinks they can meditate on a mountaintop for 21 days without food or water just because some book says that they can, they will probably end up dead.
In my experience, so-called breatharianism isn't really advantageous over eating. The only real practical use for breatharianism would be to survive if you somehow could not obtain any food. This is an extremely unlikely scenario, as almost every environment on the planet contains edible things if you know how to obtain them.
There is a good reason we don't see any good evidence for permanent breatharians. I think it has less to do with whether it is possible, and more to do with the fact that there is almost no situation in life where breatharianism would be practical (even if one did know how to do it)
I look forward to more debate.