Are you trying to make me feel old?

Back in my day, that used to be the only way a computer could produce sound. Later on you could purchase a specialized sound card that would take up a slot in your motherboard.

They do, but it’s a very simple speaker that’s really more of a buzzer than what you might think of as a speaker.

Many motherboards use a combination of beeps to report hardware errors if you fail on power on.

Bleepers

386 era machines often had a 4 inch speaker in the front panel. It couldn't do much. Some main boards still come with headers for a speaker, some even come with an electret beeper

Beep beep

Slightly related, it is really annoying you cant stop the boot speaker on the PS4 without voiding your warranty and ripping the speaker out

A good number do, but you won't hear anything during normal operation. If your vomputer has ever beeped at you when you try to turn it on at 0% battery, accessed the bios, etc., there's a good chance that was the motherboard speaker.