Ever heard of the term "vocal minority"? And there are many other advantages in PC gaming besides graphics and power.
Yes, but let me just tell you that most actually do care about graphics and if steam is a vocal minority than PC gaming doesn't exist since physical sales are practical non-existant.
You are doing it again. Only a very small fraction of Steam users will ever post in the Steam forum, the majority will buy and play their games without writing about it. The same goes for the majority of console, handheld and mobile gamers.
What other advantages? PC gaming is rarely cheaper than console gaming. Yeah you can do more with a gaming PC but you can also do the same stuff with a cheap Netbook and who doesn't have at least one PC already these days.
Free choice of the controller (gamepad, mouse, keyboard, touch screen, flight sticks...), free choice of the game setup (some prefer better resolution, others prefer higher framerates, others prefer better antialiasing, others prefer better special effects, others prefer multi-monitor-widescreen-gaming, others prefer stereoscopic gaming, others prefer to game on more moblie devices like gaming laptops, ultrabooks, netbooks or even windows tablets...) instead of the one-size-fits-all-approach in console gaming, indie bundles, playing older games in the best possible way without rebuying "remastered" editions, modding, total conversions like Nehrim, emulation, point&click-adventures...