I'm not thinking transaction fees: multi-sig that doesn't use taproot strikes me as foolish unless it's old. I'm thinking usability.

To spend from a multi-sig, you have to go collect enough keys from your hiding places. That's great for a long-term vault, but not if you might pull funds more often than once a year.

Shamir allows spending from a hardware wallet, but doesn't have single point of failure for the seed backup. Balanced trade-off. At least for those funds not set aside for retirement.