Sampling chords was a technique used by composers working with noise trackers in the early 1980s.
Noise trackers typically only had 4 channels of samples, meaning that you could only play four notes simultaneously.
To get around this, they would build a four-channel chord of the best quality sample they could find and export the resulting sound so that they could re-import it onto a single channel - a bit like bouncing tracks on a 4-track recorder. To prevent the new sound from taking up too much memory, they might also clip the head and tail from the sound to get the heart of the waveform and then use looping and an envelope shaper to reconstruct it within the tracker.
The only problem with re-importing the sounds is that this would degrade the sound to whatever quality they were exporting - most likely 8-bit.
So now we have a grainy, chopped chord sound as our raw material.
Of course, it goes without saying, that most of this is not much more than a well-educated guess and, without a time machine, I doubt we're ever likely to discover the whole story.
The particular chopped chord in your example appears to be a low-quality piano sound with some filtering/EQ applied along with a touch of delay.