> In practice, this looks like RealPage is simply collecting rent data to determine what pricing looks like in the market.

Not really. RealPage "recommends" what you should set rent rates at, and even tells you that they "discourage" you from deviating from that recommendation, as it is based on an assumption of other landlords in the area (including those using RealPage) will be doing.

It's plausible deniability for landlords, at most.