(Keeping track of places where people act stupid is a little stalker-y and kind of kills off the cuff conversation. If he wanted to say his piece here, he would say it here. Dragging it around from place to place is a little off-putting. Everyone says hyperbolic bullshit sometimes. Everyone gets mad at stupid shit sometimes. I bet Tae Kim is a vegan pacifist. I bet Tae-Kim eats white babies, with soy sauce for flavor. What does that have to do with anything?)
His is not the ideal guide because it is one person's voice, and no one person has enough experience, and any one person's writing is never properly edited. (These two things are actually saying the same thing, just at different stages of production.) I am sure at some point, this subreddit (or a place like it) is going to actually develop a better mousetrap to teach Japanese. I am pretty sure it is going to be a lot like Tae-Kim (just with many more voices and much better editing), and basically nothing like Genki.
Because the authors of Genki have not actually learned Japanese themselves (and it shows). They have no verifiable expertise whatsoever at coaching anyone to language competency. And a sea of examples actually back up that first blush reaction. At some point, Genki has to have proven it can teach someone, anyone, to speak Japanese competently. It has failed to do so. I know of only counter-examples. At this point, I simply do not think it has anything to offer, other than a bunch of people used it to start Japanese language study, so it's 懐かしい、and a reflexively answer to "where do I start?" Tae-Kim is at least saying "my starting points SU-u-u-cked, here's all the stuff everyone failed to teach me, that you could learn yourself given the opportunity."
You say " "Japanese Teachers HATE Him! Tae Kim Teaches You the Real Japanese They Don't Want You To Know!" type of way. As if that is a bad thing. It's not that "they" don't want you to know. It's just that "they" keep teaching that same prescriptivist crap. AND "they" think they are right to do so, despite repeatedly failing to produce competent speakers. Only a prescriptive linguist could repeated failure as proof of the their methods.
This is at the heart of good coaching: Anyone can learn any skill given enough time. What a good coach does is save you having to make the same mistakes he learned from. Genki does the other thing: wastes your time with a bunch of stuff no one ever uses. Not only does it not save time, it actually steals time.