[bluGill]

Many synthesizers have limits on how many sounds they can support. Midi was originally started because 1970's (analog) synthesizers could only produce one sound and so they wanted a way to have several synthesizers connected together. Before midi was finished synthesizers (now digital) could play more than one note. Though hardware limitations (not just software) didn't support infinite notes and so until around 2000 that synthesizers could generally play enough notes that players wouldn't run out in the real world.

[officeplant]

The companies that came together to make MIDI all had analog polysynths capable of true polyphony before the MIDI standard was even finished. (distinct osc/amp/filter outputs per note and not just paraphonic synths that shared AMP/Filter circuits between OSCs)

MIDI was more about unifying the entire studio of synths, samplers, drum machines, and recording equipment. And creating interoperability between various manufacturers of music equipment. It was a solution to the multiple control voltage standards that predated it and made it troublesome to tie equipment together.

[Earw0rm]

Yep, and not forgetting that serial ports on a computer were (at the time) expensive, and the sounds most synths were capable of were.. kind of simple. So there was the motivation for stacking multiple synths up to produce bigger/richer sound, doing keyboard splits (possible on some hardware of the time but not most), as well as driving many devices from a single port.

Multi timbral synths (different sounds addressable per MIDI channel) were a later thing too, analog polysynths could play more than one voice, but very few could play more than maybe two different _sounds_ at once.

[bluGill]

Right but the conversations started before then.

[kevin_thibedeau]

Polyphonic analog synths existed before MIDI. Notably, the Novachord from the late 30s. For the modern era, analog 2-8 note polyphony was available by the late 70s.

[dhosek]

It was well before 2000. Most of my gear is 1990s vintage and while some has limited polyphony, most has unlimited polyphony and doesn‘t do note stealing.