I think what they (poorly) meant was that there shouldn't be individuals/entities that own multiple houses, to give everyone/more people the chance to own homes. There is a serious housing shortage because a lot of people and companies buy multiple homes. Some use it as basically a form of money (notably the Chinese) and others use it as a form of income (Individuals/entities that own 10 or more affordable/family homes and rent it out. Airbnb was/is a huge contributer to this issue)

As a rule, people today cannot buy homes and rent is a major reason why. In most places rent is over 60% of the average paycheck. How are you supposed to afford a house? You won't even get accepted for a mortgage with the average paycheck. This issue has a lot of consequences, suchas the birthrate is falling at an exponential rate. It's barely at the replacement level, and in some places, below. And the trend is continuing.