This is the natural result of policies that make it difficult to build new housing. Landlords only have immense power in areas where demand outstrips supply.
You still have to break up price fixing cartels like this. You can't just lean back and pretend "moar supply" will magically fix anything.
The cute comments ("moar supply") signify your ignorance on the various aspect of the housing market at large. And that is an unproductive comment that demonstrates your overall lack of understanding of the issue at hand.
This "cartel" is a symptom, not a cause. Nobody is price fixing sedans, are they? I wonder why. Oh, supply of hundreds of options and price points? Hmmmm....