Are you aware of Valve's history?
Half-Life was made just by Valve people and was their first game (other than the cancelled Prospero, but that does not count since it was cancelled)
Counter-Strike and all it's sequels/remasters/whatever are buying the people making the game
Team Fortress and Team Fortress 2 was hiring a modder that made the original.
Portal was hiring a small team that made a game at a school.
Left 4 Dead was picking up another studio that made a game with a similar idea, and was adapted into what became Left 4 Dead. Valve's version of their original game was even released as a free game on Steam (Alien Swarm).
Dota 2 was hiring the modders (Icefrog and Eul) that made the original.
Artifact and In the Valley of the Gods you already know about.
Bottom line, you could make the same argument you're making for ALL of Valve's lifetime. These studios or modders they buy ARE part of Valve, they work for Valve, they get paychecks from Valve. There may be situations where for instance, they hired Hidden Path to make CSGO when it original came out, but Valve took over maintenance of that. The former Campo Santo people are Valve now. You can't just pick and choose games to not count as games and keep the others because you like those games.
I didn't even mention the VR games, hardware endeavors (Steam machines, Steam Controller, Steam Link, Steam Link phone app, Steam Broadcast, etc.), and other ventures.
Valve makes games. They may not make the games you personally want, but they make games. I personally like Artifact, but it flopped massively. Lots of people did not like it, and they're entitled to that opinion. However it's straight up false to say they don't make games. They also maintain Dota, CSGO, TF2 (albeit to a lesser degree now), and even are STILL going to persist with Artifact as patch notes from that as recent as this week said they are still in this for the long haul. I really hope they can turn Artifact around, because it's a great game.
