The difference here is that these are all editorials. Not based on a concete release, piece of news, or press release with information worth publishing. A bunch of people decided "hey, I have *this* opinion and I'll write about it* at the same time with almost the same opinion.
That's... how many/most editorials work. They're opinionated responses to things. They happen any time something big and culturally relevant happens. Look at how many editorials there were about Orson Scott Card before the Ender's Game movie came out, or how many writers decided to share their opinion on whether or not it was moral to eat at Chick-Fil-A. When notable stuff happens, a writer's instinct is to write about it.
I was the Opinions Editor for my college newspaper for three years (and a columnist for 3.5). I published two to three columns a day, five days a week, and many of them were responses to things in the news, editorials from larger papers or even (on occasion) responses written in reaction to things other columnists said
in the same paper. Sometimes, by pure coincidence (as they didn't usually talk to each other), two columnists would turn in columns that covered the same exact topic. I believe (though I admit my memory might be failing me on this one. It's been a little while) there was even at least one case in which I opted not to publish one person's column because it was too similar to one that had just run.
To address your other concern: I can tell you, as someone who is in the GameJournosPros list (unlike most of the "gamers are dead" authors, as M.H. Williams already pointed out), not everybody in that group thinks the same way. You think a collection of 150-ish writers from across the country/world all had the same views on the same topics? No. There were a lot of arguments. A lot of debates. Most of it civil, but things sometimes got heated. Heck, more than one discussion was focused primarily on how quickly print magazines and newspapers are dying. You think I was excited to agree with that idea, considering I work full-time at a newspaper?
If you think anyone in that group, Ben Kuchera or otherwise, was able to "bully" me into bending to their editorial whim, you are very mistaken. Personally, I report to an editorial board that is completely divorced from the video game industry. My loyalty is to them, not a group of peers I maybe see in person once or twice a year.
Also, if it were true that the people in the Google group had somehow coordinated the "Gamers are dead" articles (which wouldn't make a lot of sense for a lot of reasons, not the least of which being that I don't know what the purpose would have been), Breitbart would have leaked the relevant e-mails. There wouldn't have been any reason for them not to. So unless there's some
other mailing list (one that is apparently more secret than the one that was openly mentioned on Twitter more than once) that I've never been part of, I don't think the idea that writers coordinated these articles holds any water.