block – CoinbaseTx Id on Witness Dedication Markle Tree

The witness dedication situated in a single output of the coinbase transaction incorporates:
OP_RETURN commitment_prefix|witness_commitment

The place commitment_prefix=0xaa21a9ed and
witness_commitment=sha256(sha256(witness_merkle_root|witness_reserved_value)).

The witness_merkle_root is the foundation of a Merkle tree containing all transactions considering their witness knowledge. For the coinbase transaction we can not use the true hash of the transaction, as we’d have a recursive dependency. To resolve that we use all 0s:

                             sha256(sha256(E | F))
                                        │
                     ┌──────────────────┴───────────────────┐
                     │                                      │
        E = sha256(sha256(A | B))               F = sha256(sha256(C | D))
     ┌───────────────┴───────────────┐      ┌───────────────┴───────────────┐
     │                               │      │                               │
     A (CoinbaseTx)                  B      C                               D
  000...                         txid_2  txid_3                         txid_4

Why will we use a tx id set to all 0s as an alternative of simply ignoring the coinbase transaction to create the Merkle root?

The witness dedication situated in a single output of the coinbase transaction incorporates:
OP_RETURN commitment_prefix|witness_commitment

The place commitment_prefix=0xaa21a9ed and
witness_commitment=sha256(sha256(witness_merkle_root|witness_reserved_value)).

The witness_merkle_root is the foundation of a Merkle tree containing all transactions considering their witness knowledge. For the coinbase transaction we can not use the true hash of the transaction, as we’d have a recursive dependency. To resolve that we use all 0s:

                             sha256(sha256(E | F))
                                        │
                     ┌──────────────────┴───────────────────┐
                     │                                      │
        E = sha256(sha256(A | B))               F = sha256(sha256(C | D))
     ┌───────────────┴───────────────┐      ┌───────────────┴───────────────┐
     │                               │      │                               │
     A (CoinbaseTx)                  B      C                               D
  000...                         txid_2  txid_3                         txid_4

Why will we use a tx id set to all 0s as an alternative of simply ignoring the coinbase transaction to create the Merkle root?