Does the reference client Bitcoin Core determine the consensus rules?

[Bitcoin]

Does the reference client Bitcoin Core determine the consensus rules?

Does the reference client Bitcoin Core determine the consensus rules? Why should we care what is in the BIP if when there is a discrepancy between the BIP and the Core codebase (like we saw recently with Core's implementation of BIP 125, admittedly for policy rules rather than consensus rules) the BIP is ignored?

Source: Does the reference client Bitcoin Core determine the consensus rules?