I agree that if there have been a substantial number of people fired recently, that should be possible to dig up either via LinkedIn or anecdotally from people in the industry (of whom there are many on ENWorld). However, the source does not claim all these firings were recent -- they might be spread out over the last year or two.
I also note the word "reportedly" in the section that is quoting the source -- i.e., it is the source who is saying "reportedly," not DND_Shorts. Now, this has been run through a bot so we don't want to read too much into the precise wording; but "reportedly" suggests that the source is giving us secondhand information about the firings. And it is often very hard to get the straight dope on exactly why a coworker was fired.
I don't question that DND_Shorts is accurately reporting what they've been told, and I'm quite ready to believe that the overall atmosphere at WotC is as described. However, we are getting one very narrow glimpse of what's really going on. I'll be interested to see if Linda Codega picks up this one, and if so, what they dig up.