Oh, yes they did. I’ve read the entire 36 pages of that thread, and over and over the disgruntled users of the site have been very specific in their complaints:
They object to an independent book discussion site, which to date has never favored any one reading platform over another, being sold to a company which has a vested interest in promoting one particular reading device (the Kindle), which ultimately aims to monopolize the bookselling market, which has actively discriminated against certain categories of books and authors in the past, and which can reasonably be anticipated to engage in data-mining their accounts.
How is that not a specific objection?
To anyone who values independently-run, community-centered websites, the buyout is unquestionably a bad thing. That is absolutely without question.
If you woke up one morning to discover that your town’s mayor, acting on his own with no input whatsoever from the townspeople, had arranged a deal with Walt Disney Corporation and sold the local parks, the community center, the public library, the public schools, the town hall etc., to Disney and that you were now effectively living in Celebration, would you be OK with this? Would you be OK with being told “just move if you don’t like it,” as if selling your house and leaving behind the community you had dwelt in for years was a trivial thing and posed no difficulties whatsoever? Would you be OK with being told that your complaints about the mayor’s actions were “whining”?
Or would you think that the fact that your town could effectively be sold out from under its residents without their consent was a problem?
Of course, the mayor of your town CAN’T unilaterally sell community owned town property; here in meatspace we have laws preventing that. Unfortunately, the same does not hold true in cyberspace. Cyberspace has yet to work out a way to create truly public spaces, and that is a genuine problem. Many, many community run websites have been sold out from under their userbase and subsequently destroyed by private interests intent on monetizing social interactions. Why shouldn’t the users of Goodreads who fear that this is what’s just happened to their site complain about it?
Frankly, I find their attitude a lot easier to understand than yours.