There aren't that many games that only supports the stereo DAC output of the Sound Blaster Pro, but not the Sound Blaster 16.
As I recall, one exception is Wolfenstein 3D, which only supports the Sound Blaster Pro's stereo DAC as well as some demo's (from your demoscene groups).
Also to consider is that the Sound Blaster Pro was released in 1991, followed by the Sound Blaster 16 in 1992 (basically a year later).
Back in 1991, sound cards were still very expensive and, those that could afford one, were still buying Adlib & Sound Blaster (mono) sound cards. Stereo output was then considered to be a novelty and game developers only started to support stereo DAC output towards late 1992.
In the early days of digital voices (DAC output), I think that stereo output wasn't actually that important, since the DAC was mainly used for sound effects and voices (which didn't necessarily require stereo output).
It was only with the advent of first person shooters (like Doom) when stereo output became more of an importance to game players.
