You‘re confusing this with the arpeggiator, which is not available for midi tracks. Chord mode works on midi tracks just as well as on audio tracks.
To me, the question by dave_angel is a great example why there is the community rule about AI slop (Ch4tGPT / 4I slop: not here, please! ). ChatGPT‘s answer is bullshit in every respect (audio tracks sending out midi? where did it get that from?), LLMs just are not useful when looking for reliable information about factual questions.