Many community organisations rely on the work of volunteers to keep them afloat. Ausfish is in the same category. Steve Brown says that there are over 1.3 million posts on Ausfish that can be read for free. That's fantastic - they represent an enormous body of knowledge and skills compiled over a very long time - and many of them are mine. But all of those posts were put up on the website by members voluntarily. Their motivation, in most cases (certainly mine) was to help fellow anglers who might not have as much experience fishing for certain species or new locations or trying new techniques etc.
When a new member joins and wishes to make a post he/she is saying 'can I add something to your knowledge base?' If you say to a volunteer who wishes to make a contribution 'Yes, but only if you pay us' many will simply say 'Up yours' - or words to that effect, as my mate did. I would also expect (although I have no evidence except my own point of view on this one) that the more experienced the member is, the less likely he/she is to pay to contribute.
An organisation which actively discourages the voluntary contributions of its members will inevitably be poorer as a result.
Cheers Freeeedom