I think the reason people here feel this way is because the general consensus among HN users is that the best product wins and that's all that matters. If a company has a monopoly on data and refuses to provide an API they're saying that they don't want to compete on the quality of their product (craigslist for example) they want to keep their position without the benefits to the users. Padmapper made craigslist apar…
I don't think Craiglist has a "monopoly on data", they have a monopoly on their data and they have not incentive to make their data freely available.
In the past, do you think anybody ever looked at the classifieds page in a newspaper and thought "this data is owned by the Times"?
In the PadMapper case, who are the losers? Renters benefit from a radically different UI and de-cluttering of daily reposts. Owners benefit from the increased traffic to their listing. Craigslist benefits because it's more of a 1-stop-shop for owners: post to craigslist (and pay them), and get some level of syndication to different services and apps. They also aren't losing out from reduced mindshare of renters: when you use PadMapper you know you're using Craigslist. It's always obvious and all links point there.