But you can use seed phrase to create the wallet without the use of the master public key too? The seed phrase can generate the master public key.
Yes, but doing so is pointless. If you are going to create or restore the wallet only using seed phrases, then why have a multi-sig wallet at all? The whole point of a multi-sig is to remove the single point of failure. Each wallet should only be created or restored using a single seed phrase, and the master public key from all the other shares, so that any single wallet is insufficient to spend the coins. If you are going to create or restore your multi-sig by putting all three seed phrases in to the same device, then all you have achieved with your multi-sig is increasing the size of your transactions and the fee you have to pay.
Each seed phrase should never leave the device on which it was generated, other than to be written down by hand as a back up. The only thing which should be transferred between devices are the master public keys.