

I think the point there is that the government of the day cant just overrule him by saying so. If it comes down to it, in an supply emergency his word goes until the government either change the law or get one of these “Order in Council” directives signed off by the king.
It doesnt mean that much as it seems very unlikely that the monarch would refuse the PM something like that, but crises are where the unthinkable happens.
You’re missing the key word there which is “overnight”. Sudden dramatic changes rarely work out well for anyone other than people speculating (or having inside knowledge) on where the cards will fall.
Phasing out landlords over, say, 3 years would be a great idea, banning them tomorrow would not be.