Over the years, many companies have contributed to free software development. Some of these companies primarily developed non-free software, but the two activities were separate; thus, we could ignore their non-free products, and work with them on free software projects. Then we could honestly thank them afterward for their free software contributions, without talking about the rest of what they did.
We cannot do the same with these new companies, because they won't let us. These companies actively invite the public to lump all their activities together; they want us to regard their non-free software as favorably as we would regard a real contribution, although it is not one. They present themselves as "open source companies," hoping that we will get a warm fuzzy feeling about them, and that we will be fuzzy-minded in applying it.
This manipulative practice would be no less harmful if it were done using the term "free software."