The article mentions how important it is to keep availability status accurate:

  Before I get into the solution, I should explain why 
  these renters have such persistent trust issues.
  [...]
  Because messaging/applications/leasing were all 
  on-platform for us, we could know when a lister was 
  unresponsive or a lease was signed. That insight naturally
  allowed us to reliably prevent stale listings. Critically, 
  however, new renters to our website didn't know that. And 
  they wouldn't believe us when we said it. We were in a bit 
  of a pickle.

When sampling listings in Manhattan, the second one I came across was in fact not actually available [0].

  “Hi, this unit has been rented, what exactly are you   
  searching for?“

[0]: https://apartment.app/listings/2-bedroom-west-53rd-street-ne...