This is very dangerous because if the court disagrees, the tenant will be held responsible for unpaid rent until the apartment can be leased to a new tenant plus the cost to the landlord of finding a new tenant. Historically, constructive eviction was one of the only ways to get out of a lease if a building was unlivable. These are a series of responsibilities a landlord cannot dispel through a lease. If the landlord has violated one of the promises, the tenant is better off filing a rent escrow claim than trying to claim constructive eviction. Actually, the Plain-Person's Guide is not as biased as the author originally intended.
Tenants have since the earliest days of landlord-tenant law been on the bottom.
In England, where our laws come from, it was assumed that only God could own land but that God vested the right to give out land to the King. Lords gave it to sub-lords and so on, until the land was finally leased to the people to lived on it, called serfs. Therefore, the founders of the U.S. reformed the law and adopted relatively liberal policies to tenants. The idea was that landlords are in a more powerful position and the state has a moral obligation to intervene and even out the playing field. Finally, if you're not satisfied with that answer the founder's of the U.S. inserted verbiage into our constitution permitting anyone to say anything they want to.