BIP342 enables a type of payment called Pay-to-Taproot, which allows users to transact via a Schnorr public key or other ways.
If Person A send Person B 1 BTC, but Person A only wants it to be given to Person B after a number of conditions are met, then all of those conditions would be visible on the public ledger, which could compromise the privacy of Persons A & B.
“When Bitcoin is sent to a MAST output, the Bitcoin is locked to the Merkle root of these scripts, and to redeem the bitcoin, the spender must reveal the script which they are using to unlock the bitcoin, as well as proof that this script is included in the Merkle root of the previous transaction,” according to a research paper.
The Lightning Network, Liquid, and other sidechains use scripted rules like multi-sig and hash time locks to make their scripts secure.
Since only one signature is computed to represent all parties, less information is recorded for each transaction, and there is an increased degree of privacy.