The survey doesn't show up when you are in big picture mode. Since Steam machines boot into big picture mode, they will never get the survey unless they switch over to desktop mode, which takes some effort. That would account for some of the Linux under counting.

It just shows that Valve themselves don't take that survey seriously, if they don't even count specialized hardware targeted for SteamOS. So I wouldn't use those numbers for any far reaching conclusions.

Nobody uses SteamOS or Linux for gaming. It baffles me that people like you go to such lengths to push Linux for Desktop...

I tried using Linux on several occassions over the last 10-15 years. It was never easy or fun. All the GUIs felt like they were from the 90s and nothing worked out of the box. I tried Ubunutu, Mint, Arch, and a few others. My last attempt at it was ~2014. Maybe I'll hate myself enough to try Linux again in a year or two...

It baffles me when people use the "I couldn't get it to work so it obviously doesn't work for anyone" argument, even in the face of statistics that prove otherwise. Ho hum.

I suppose you should use it today, instead of making your impression on the times long ago, and claiming Linux isn't usable because of some long gone issues.