First of all, the author is wrong. Someone saying "Hey, I know that person, they're an expert on X," does not mean they belong in an encyclopedia. Furthermore, a sizeable group of people already had a discussion on whether the person meets Wikipedia's standards and decided that they do not. Now, the author feels entitled to barge in without learning anything about how Wikipedia actually works, and complain that it's…
I spent a half-hour just trying to find the right form to merely request that the page be reviewed for restoration. That form, as I explained in detail, doesn't actually work. There is no form for pages that have been deleted. There is a page only (as best I can tell) for pages that are under consideration for being deleted. Once they are gone, they're gone -- unless they were removed for the ill-defined uncontrovers…
This happened all the time in my domain of expertise (information security), and it was exasperating trying to beat it back. Some jackass would write an article about himself and then tie up AfD for weeks claiming that the trade press quotes he got constituted reliable source coverage of his notability, while his friends and coworkers would jump on saying "I've worked in this field for 7 years and I can tell you that everyone in information security knows this guy is one of the most important" zzzzzzz Strong delete speedy delete delete with fire.
Whatever trouble you feel like you had with Wikipedia's interface: your friend got a very fair shake in the AfD debate. She wrote a non-notable book, and was quoted in passing in a couple articles, and that's basically it. People took real time out of their day to verify the pretty-obvious fact that your friend doesn't need to be in the encyclopedia. Stop being angry about that.