I tend to still buy intel for new desktop builds - I'm not really bottle necked on the cpu for most of my computing needs, so I prefer the built in gpu for ease of maintenance and the better power efficiency (particularly idling, where intel still tends to do better).
But my Deck means I'm showing up as AMD for most of my steam usage over the last few months.
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To avoid just being anecdata - I went and looked up some numbers (on google, they might still be wrong). As best I can tell, Steam claims about 1.9 million monthly active users on linux (may - 2023). Steam also claims that sales of the deck surpassed 3 million total units in 2023.
So 50% of steam decks can end up buried in drawers somewhere and the steam deck would still be 70% of the active linux userbase.
The only reason I care about the number of Linux users is because more users means more development resources. Using that criteria, Steam Deck users very much “count”.
That's technically true, but oversimplified enough to be misleading. SteamOS boots from a read-only OS partition from which you can change nothing. You can only write to your "home folder", and you can only add new software using Flatpak, or Steam itself.