Laserdisc did have digital soundtracks added in a few years after the launch of the format.
While there is no difference in resolution between CAV and CLV laserdisc, only CAV gave single frame stepping (I do have a laserdisc player which "simulated" single frame stepping on CLV discs by using a digital cache but this is not my daily machine).
MPEG is a digital compression algorithm and laserdisc, while it had it's flaws, did not compress image content.