Because it's out of character. On Steam there are practically no restrictions whatsoever on what you can say in reviews. Even completely irrelevant, off topic, risque, or meme spam reviews are perfectly kosher. A reasonable and relevant review being removed makes 0 sense, and is not something Steam would ever do. So it's obviously somebody who's working for them, that shouldn't be.

Of course I do agree with you on accountability. Companies should not use volunteers for remotely relevant positions. If they do, and those volunteers screw up, it's on them.