Some more pros for SS+P:

The wallet balance isn't so easily revealed, as one doesn't need to backup any xPubs.

The backup process itself is much easier (perhaps this is what you mean by "simpler"). For SS+P, everything can be human readable and etched on steel. For multisig you again have the issue of backing up all xPubs, which are either digital or on paper. There should be multiple copies in case of bitrot.