"Recently there's been a bunch of community discussion around what kind of games we're allowing onto the Steam Store.
As is often the case, the discussion caused us to spend some time examining what we're doing, why we're doing it, and how we could be doing it better. Decision making in this space is particularly challenging, and one that we've really struggled with.
Contrary to many assumptions, this isn't a space we've automated - humans at Valve are very involved, with groups of people looking at the contents of every controversial title submitted to us.
Similarly, people have falsely assumed these decisions are heavily affected by our payment processors, or outside interest groups.
Nope, it's just us grappling with a really hard problem."

> falsely assumed these decisions are heavily affected by our payment processors, or outside interest groups
This was written in 2018 and they still claim the most recent sweep was "their own decision"

https://steamcommunity.com/app/593110/eventcomments/1628537372818538426/?ctp=1