So the books are OK. While it would be hard to become a disciple of all those authors, I guess they put their teachings into a written for in order to be known by many, inlcuding those who do not even live in the same country, or same continent, or speak the same language. A common thing in those books is that they present Dzogchen in a pretty accessible form and they also explain methods to practice it. Suppose I read one of them, understand it, then practise it - isn't that Dzogchen practice? If not, then what?
I'm bringing this up only to give an example how it is possible people don't necessarily associate Dzogchen with other tantric practices. And that is not because they don't want to but how Dzogchen is presented. Similar to Vipassana and Zen.
It's simply impossible to practice Dzogchen without a qualified vajra guru. And books and even webcasts are wonderful exposure, but don't arm a student with the blessings and introduction needed to practice tantra. Reading books or hearing podcasts, or watching Internet events are not equivalent of receiving the abhishekas. You have to literally be in front of the guru for that.
So while reading and studying is good, it's very good! It's not the same as practicing under a qualified guru. For this one must seek out the proper initiations. And that is what will make the difference for the student. A big difference!
People may try to present it otherwise. I've seen folks try to say otherwise, in fact. Perhaps out of wishing, or misunderstanding. But it's just not so.
ps. please excuse any repeats here, I haven't read through the whole thread