Go back five or six years and you might have heard about the prospect of a Steam Machine or Steam Box, and the hopes that it would offer the convenience of a games console for would-be PC gamers. In reality the idea of a dedicated gaming PC running SteamOS never really took off, and now it seems Valve is adding nails to the coffin.
As spotted by PC Gamer, Valve has removed the Steam Machine link from Steam's hardware tab. If you check, all you'll see are links to SteamLink, Steam Controller, and HTC Vive. The Steam Machine page is still accessible, and it's still possible to follow the links and purchase one for yourself (if you want one), but you need to use a direct link.
There were a lot of reasons why the Steam Machines never really gained traction. SteamOS itself wasn't all that great, coming with a lot more bugs and quirks than Windows 10. The Steam Machines themselves were quite expensive, and users had to contend with delays and cancelled systems. Plus it certainly didn't help that Valve offered a competing product of its own that was much cheaper.
PC Gamer points out that one of the ideas behind Steam Machines was to bring PC gaming to the living room, but the Steam Link let existing PC gamers stream games from their existing systems for a much lower price. It's no surprise that it's still readily available.