One caveat I would give for Ask A Manager, any similar websites, or most “career experts” in general (especially those who work in a university career center) is that their perspective tends to be biased very strongly towards action, even when said action is wasteful and just exhausting. Unlike what most such people would say, “Hi I’m XXX and I’m interested in your company’s YYY positions.” is a perfectly valid and useful way to approach a career fair or other career event. Similarly, seldom would you hear “meh it’s not a big deal” for thank you letters and how to send them because that’s just not their approach to this sort of thing.
Part of the reason is that most of these people have a business background. There is absolutely nothing wrong with that - there is a lot of good, important work that goes into business administration and there needs to be people who are trained in dealing with people in various capacities (e.g. in the career office, or in academic advising). The only thing is that they often prescribe a “business major solution” where it isn’t appropriate, a sort of “if all you have is a hammer then everything looks like a nail” situation. The other factor is of course that such people need to justify their existence and they have every motivation to make their work look more complicated.
You will often hear very different suggestions from people whose job it is to speak frankly than from something like AAM. And that’s not to say that AAM and the like aren’t useful (far from it), but just that they don’t take a no-nonsense approach to this thing, and occasionally it really shows. In the context of thank you letters, this means that AAM and ilk are likely to overemphasize and overcomplicate the matter because that is in the owner’s best interests.