Quake was basically the only reason to get a 486DX--floating point support.
The crazy GPU push--later culminating in CUDA and all that other nonsense--is completely due to the Quake OpenGL and 3dfx support.
High-speed internet at home was mostly useful for playing on QuakeWorld, and later derivatives Half-Life, and the Unreal series (not a derivative, but you get the idea).
So, yeah.
EDIT:
One might also point out that the death of the great workstation companies (SGI, HP, etc.) happened because they were no longer competitive in the CAD space, specifically because consumer-level graphics cards were improving driven by the demands of gaming.
and AC (after Carmack).
It is a simply game but it changed the course of history in terms of what direction gaming went, thus the heavy hardware designs to support that type of games.