I'm not sure if this applies to the OP and am certainly not inferring that they were rude etc.
rule #1 is not to mention the existence of the flat tire rule to the agent. It's never been published in any public-facing document.
Basically it's a courtesy in their employee system that has to be offered by WN rather than a privilege that a customer can demand.
Perhaps official protocol changed and they are to inform the customer on the new no-show policy before looking to rebook them. Perhaps it is now at the gate agent's discretion. Showing up out of breath (or in tears) shows more legitimacy than stumbling over from the bar, or telling an agent that you booked a cheaper flight knowing you'd likely miss it.
If it's a definite change in policy then I'm sure we'll soon someone on FT say they had to re-buy a new seat. IIRC, I think that is already Jetblue's policy.