Yes there are other formats such as DTS and Auro 3D. You can even do it with straight up LPCM if you want, but DD is one of the quickest ways to do it and iirc DTS has similar licensing requirements with their logo, and barely anyone has Auro. You could try to use LPCM but you’d need a multichannel output such as 6x analog connections or a digital source using bitstreamed output which many didn’t have at the time.
Yes there are other formats such as DTS and Auro 3D. You can even do it with straight up LPCM if you want, but DD is one of the quickest ways to do it and iirc DTS has similar licensing requirements with their logo, and barely anyone has Auro. You could try to use LPCM but you’d need a multichannel output such as 6x analog connections or a digital source using bitstreamed output which many didn’t have at the time.