Economists disagree.
The change in IHT in this budget encourages people to stay in larger homes for longer than they otherwise might (and their descendants to keep the house as an asset rather than sell it) thus reducing supply to the market and increasing prices. The parliamentary report I linked earlier refers to this explicitly;
"John Muelbauer, professor of economics at Nuffield College, Oxford, suggested a new higher threshold would choke off the supply of new properties: "In the majority of estates, housing is the most important asset. Many families currently liquidate that asset to pay the IHT, which means that homes come onto the market. If people can hang onto family homes for longer, this will cut supply and prices will rise."" (my emphasis)