Soy is great, when its prepared correctly. Its my understanding that where Soy was explored is in Asia, however they do not consume as much soy as we do and when they do it is generally in a fermented state.
Soy milk often is not fermented and is actually difficult to digest. When its been fermented however, in a miso form, or tempeh or natto for example, its ready to be taken in by the body.
So somebody can say 'soy' is good for your health and apply it to the milk, however really, its not that great in the milk form, but in its fermented state.
Personally, I have low amounts of the milk and the one I buy in Australia has been slightly fermented through organic processes. Without that fermentation, digesting soy is actually more difficult than digesting some meats and can be quite harmful.
Buddhists have a teaching about reaction. And what we have here is the lesson in reaction. When you move from one thing to another, without firstly taking a moment to consider the whole situation, you actually go and create the same problems you moved away from. Potentially just as much damage is being done in the world now from Soy crops to the earth, and damage to the uninformed person on the incorrect preparation of this bean for eating.
Just consider that before the people who invented the eating of this bean need to have it sit and pretty much ferment (e.g breakdown in a barrel) for a few years before they will eat it. Then consider that most soy milk is probably simmered for a few hours and its very thick proteins etc are released into a liquid which our body actually finds hard to digest and yes, it can block the system up.
Try this - go buy some beans (i have done this) and cook them yourself. See how long they take to actually break down. Its virtually impossible. Its the tough nature of the Soy that makes it so usable for many things.
Consider the linings of your stomach... buy some soy milk and heat it up in a pan. Let it sit for a little while. You will probably need a really tough scourer to remove it from the metal. What do you think is happening to your insides if this is how hard it is to get off other surfaces?