There are a couple things about that article that need to be raised.
1. The article does not take the extra step to identify what plugins or conditions are responsible.
What that means is that the author is simply collecting evidence of random infections, which does NOT help you or anyone.
What is important is to find the vector of infection, the cause. This article is not concerned with that. It's like saying, OMG fifty cars have a flat tire. So what?
The article is essentially useless because it does not tell you what's wrong. It might not even be WordPress, it could be sites using EOL versions of PHP.
2. 15,000 sites is really not a big deal. You know how many 15k vulnerabilities there are? About a dozen pop up pretty much every day. It's like, wow man... yawn. That was literally my response the first time I saw that article.
Here's a bigger deal. There are five plugins for WooCommerce that have over 135,000 vulnerabilities.
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