AC97 (1997) was the first blow - this was Intel's improvement on the defacto SB16 interface (and not compatible with it) and was around the time audio started b

AC97 (1997) was the first blow - this was Intel's improvement on the defacto SB16 interface (and not compatible with it) and was around the time audio started being integrated into motherboards. This is also around the time it started to be common for pre-built systems to integrate functionality into the motherboard, such as VGA, audio, USB, and in some cases even AGP video all as part of a chipset. The peak of PC audio probably matches the peak of the "HTPC" wave that happened in the first half of the 2000's - PCs designed to be put under your TV and replace your stereo. But also, laptops started getting cheaper and more popular as the late 90's turned into the 2000's and beyond - where integration of components was even more valued. Then smartphones started to take over in the 2010's. The culture is different now. These days, the young people don't have stereos anymore, they might have at best have a TV soundbar or some really good wireless speakers, or a couple of bluetooth speakers, and the phone is the centerpiece of the personal audio experience now. Hi-Fi that's not dedicated to making your car rattle or be \blasted at 500w-per-channel volume over a bar/club PA speaker is dead. Desktop PCs are for businesses which need only good enough audio for business purposes, and gamers who probably want to spend money on a GPU over audio.