That makes sense.
In my motorcycles I would brim the tank with cheap unleaded before storage (Mid October to March) and never had a problem, the brimming was to prevent condensation in the tank from causing corrosion or allowing the condensed water to collect in the bottom of the tank and wreak havoc there.. Don’t know if car tanks do the same, but even if they did it’s unlikely to be an issue over the time you have the vehicle.
For the lawnmower, I service it each spring, removing and cleaning out the carb and draining the tank is part of that (bunged the old fuel into the car – a wee bit of stale fuel mixed with 50l of new wont do any harm!).
In life, it's not who you know that's important, it's how your wife found out.