I don't know about Macs, but Windoze has for a long time (but not now ?) been supplied with something called Microsoft GS Wavetable Synth, and this has been set as the default midi playback device via a midi mapper. This system does use a soundfont file (sort of). The files (on my XP system) are in the Windows\System32\drivers, and the files are GM.DLS and GM.DIS. As I understand it, the sf data is based on a (now) VERY old Roland sound canvas version.
As far as WinDoze is concerned, I'd loaded the Coolsoft Virtual Midi Synth, which in effect replaces the MS system. With that, I'd downloaded a separate SF2 file (Timbres of heaven - there are others) which is nearly 400 Mb, as in about 100 times the size of the MS-GS system! Much, much better!!
Geoff