The Paula (amiga chip) e.g. cannot reproduce a classical scale, because of limited bit precission [1], producing chracteristic harmonies.

For the SID, there's probably just not enough engineering going into emulation, as enthusiast prefer the original experience anyway.

[1] you might enjoy the talk Elements of chip music by Linus Akesson: <https://www.linusakesson.net/music/elements/index.php>