I am a Realtor in Illinois and I have represented HPoA in 2 purchases. I also sought them out to buy my personal residence, but I accepted another offer before receiving theirs. "Scam" is not a word I'd use to describe them, unless I was an uneducated tenant that didn't understand some very basic concepts of what the lease program was about. I think their website does a fine job of explaining the program and a lot of the important details. Here are the pros and cons of working with them, from the perspective of agents, tenants and sellers:
Pros:
Tenants get many more potential rentals to choose from. (In my market it gives them about 5-10x the selection.)
Agents representing a tenant can instead represent a buyer. (Commission difference on a $250k house might be $1000 vs $6000)
HPoA offers cash
Tenant gets certainty of a renewable lease and a professional management company, versus the unknown of a private landlord
Cons:
In my market, renting through HPoA means paying about 10% more than market rent. Could vary more or less
The 5% annual purchase price increase is too rich for all but the hottest markets. Planning to buy years down the road will be prohibitively expensive for almost all tenants
Standard rent increase of 3%, may be in line with the market but is not what most private landlords would do. Most tend to keep rents fairly flat to prevent vacancy
Process to buy and make-ready a property can take 3-6 weeks longer than a standard lease of a vacant home
Side notes:
I have observed HPoA list their properties for rent on MLS once tenants vacate. They start by listing for approx what the tenant was paying. This can be very out of whack with market values. They stubbornly stick to their guns for months and months before lowering the listed rent to something reasonable. In that time they have potentially lost tens of thousands of $$$ in revenue. Not sure if they are stupid and don't care, or if they need to do that to stop former tenants from coming back to rent for newer lower price.
Most potential tenants I talk to are very intrigued by the benefits, and usually the timing is the biggest reason they don't try to go forward with the program. (For example tenant needs a place in 30 days, the program can take 6 weeks.)