Before we even begin, let us bite the hate-train in the butt: the post in question has already been removed, although it’s unclear currently whether or not the removal came from Valve or Destructive Creations.
Destructive Creations is the development studio behind Ancestors Legacy, a medieval RTS that is an acceptable entry into the genre without necessarily revolutionizing anything within the RTS genre; it generally plays it safe with a rock/paper/scissors style of unit strength that RTS fans are far too aware of in the modern era, brings some interesting mechanics, and launched back in May of 2018.
Today, they used Steam News to push a product for wireless headphones that was blasted out to all owners of Ancestors Legacy; it had nothing to do with the title, or with Steam; it was simply a promotional product.
The advert gained notoriety on Reddit when a user (u/Cantebury) clipped the ad and posted it; within the comments, the Steam link was offered where users reported it.
Now the developers at Destructive Creations have received a bit of notoriety after Ancestors Legacy went under the radar for many players: at the time of publication, it has received a total of 3,113 reviews with 81% recommendation.
Depending on precisely how the advertisement was removed, this could be detrimental to the overall usage of the Steam platform in much the same way that YouTube clearly has no control over their advertisements; there are so many entities within the platform that quality control is largely left to developers.
There is a nasty future of the Steam platform where developers sell their virtual real estate within your library, hawking whatever products have the highest bidders and using their audience as a selling point to advertisers. Here’s hoping that Steam has the necessary vision to stymie that becoming a reality, and somehow manages to implement a control within the process as it stands today.