It says it right in the article's subtitle:
>Software the U.S. government says is illegal gives landlords ability to coordinate rent hikes.
The AI (in this instance "AI" just means "a blackbox algorithm") is basically an excuse to provide plausible deniability on market collusion. Combine this with the relatively inelastic nature of the demand for housing, it creates an avenue for abuse. Without the AI, you don't have collusion meaning increased competition will produce a lower and fairer market price.