I agree with this sentiment, they should try find a balance where eg an advertiser gets 5 free postings a month anything after that is paid for, similar to classifieds and its free postings vs buying a storefront.
Means the small guy on the street can still use the service, but the people running it are still making a living.
One cannot do it from the goodness of their heart forever, eventually their needs to be some other motivation or to find someone else to donate their time when you are too busy / have new priorities.