Can you explain why you feel that the miners will completely ignore the RBF flag if it is set to disable? I know it is up to the miners but wouldn't they mostly stick to the intent of the feature? I know the incentive would be to earn more money but there are many cases where the miner returned excess fee as well.
Just to mention that when the nodes have many FullRBF transacions not always win that one with more fee, here some examples, Dot with Green margin was mined, some are Testnet and other are mainnet