Owning industrial production gives you power, but that power lacks flexibility. Factories exist somewhere, need to be staffed with people that live near it, require a flow of raw materials to work on. Your power over it ends where the property line does. Financialisation lets you use existing capital as leverage; take out a loan with your factory as collateral, and now your assets are liquid. You can by shares in factories and companies all around the world -- your reach is extended and, so long as you don't default, you haven't actually given anything up to do so.