Why doesn't stereo mix have direct playback?

[DeathMetalJedi]

This is not a trick question I'm just daft... To someone who knows nothing about anything as far as audio on a windows machine, it seems crazy that to this day there's still a slight delay when listening to an output device. Why is the delay there? Is it just impossible to get rid of? Science hasn't come to a point where we can eliminate the delay when listening to a recording device? I just don't get it.

[Jaunitta 🌸]

Stereomix is applied for the software like Audacity to record from the speakers "what you hear"
So when you play music say from youtube Audicity can record it.
The technical description , back in the day on laptops the audio connection to the inbuilt speakers with the onboard chip is shared so stereomix would help with a bridge for Audacity to use to record what you hear.
On desktop the speakers are connected to the sound card.
So stereomix is for recording not playback.

Delay or echo is caused when the mic is too close to the speakers causing a feedback then interference is heard in the speakers and headphones.

[_I_]

delay is also caused when windows is using a monitoring/playback method, instead of the hardware capture/playback method