As a matter of fact, I used to do exactly that. I put 16 words in 3 locations, so recovering 2 of those parts would reconstruct the full seed.
Doing that absolutely works, but it means if a bad actor gets one of those shares, they only need to brute force 8 words (or 7 if the checksum is not in the share they stole)
Multisig means that if one share is stolen, they are still at least 24 words away from having signing authority.. and they also need the descriptor.
