I was in class one day last semester and saw a guy, while the professor was lecturing, looking up hornbooks on amazon. While this, in itself, isn't a particularly dangerous habit, it, I think, demonstrates a bad mindset that people can fall in to.
The best things you can do to succeed in law school are read and pay attention in class. Anything else is a long long long distant third. Students get so caught up in researching what the best supplement is, reading it, and trying to get an edge by going to answer-writing seminars, that they lose track of the actual best use of their time: Reading and paying attention to what your prof says.
It seems like really simple "no shit" kind of advice to say "read and take good notes in class," but I feel like maybe it's so basic that it gets overlooked. Forums like TLS hyper-emphasize how competitive everything is and, maybe, implicitly encourage readers to look for the "edge" rather than just knowing your shit and kicking ass like a boss.
I guess what I'm saying is that the gunnerish "I'm gonna do everything AND read all this extra shit" can result in a lot of wasted time - time that would be better spent focusing on the basics. If you walk into the exam 100% knowing what your prof wants you to know about the rule of perpetuities and another guy in your class who studied just as hard and is just as smart as you walks in knowing 60% what your prof wants you to know, 20% what Emanuel's says about it, and 20% of what some hornbook says, then, well, you're going to kick that guy's ass up and down the exam.
I think part of the dissection is just TLS-speak. The folks that I know don't know about this site and have done well in their classes. I think TLS just likes to overkill chat subjects that are simplistic in nature. Can some of TLS be good? Sure. Just take it in doses.
I generally agree with your overall assessment though.