Why? Because Acer modifies the Hardware ID (HID) of the Realtek chip to communicate specifically with the Acer BIOS. When you install the generic Realtek driver, the software doesn't recognize the specific tuning profile for your laptop’s speakers. You get sound, but you lose the "Acer Purified Voice" enhancements, the specific EQ curves designed for your chassis, and often, the microphone input entirely.

Device Manager: Look for disabled devices or devices with warning icons. Try “Disable → Enable” and check properties for errors.