Earlier quoted context omitted.
X.Y (e.g. 5.1) means X wide range speakers and Y subwoofers. You also sometimes see it like S/T.Y where S+T = X, and it refers to front/surround speakers. There are standard values and configurations, such as 2.0 (aka stereo) both at the front, 2.1, 3.1 adds a centre channel mostly for on-screen dialogue positioned close to screen, 5.1 (3/2.1) adds a second stereo pair behind you, 7.1 - adds an extra surround stereo…
For real enthusiasts, also X.Y.Z, adding ceiling/bounce speakers for vertical spatial audio. The real "stuck so far behind" that I don't get is why we use speaker arrays at all -- instead of binaural stereo tech. That virtual haircut demo, apparently from the 90s,[0] sounds incredible on my cheap headphones, yet the technology seems to have gone nowhere since. Is there even spatial audio in VR setups? If the difficul…
Not that that's really an explanation - if that was the best sound and it was available on Blu-rays and streaming platforms, and legacy 5.1 content upmixed nicely, then yeah why wouldn't I use headphones even at home in front of the television. Less obvious for joint/family viewing I suppose.