Now that I have your attention--"privately funded fellowship halls" is not a household phrase, let me explain. I've encountered several situations through the years where some of the members of a local church, ranging in number from 1 to many, have pooled their money and built a fellowship hall. Someone in the group, whether many or few, was not comfortable with building such a building with money from the church treasury. Is such a building scriptural or unscriptural? After all, the "Lord's money" was not used to build it, or in one case even to maintain it.
I do NOT believe the church is in the entertainment business, whether it's a simple potluck or a full blown gymnasium, with all the paraphanalia that goes into a gym. If that's true, then obviously the church could not spend it's money to build and maintain such a place. I'm not going to address the old argument that "Christians need to fellowship, so anything that helps with that is okay". Certainly Christians need to spend time together, but is that the work of the church?
In the neighborhood where the church meets (Caparra Terrace) the houses were built in the 50's. They were all built with at least one carport, even though almost no one had cars back then. What do you do with a carport when you have no car? In the tropics it becomes outdoor living area--most of them now have a TV, chairs or couches, etc. Once the carport became the family room people seemed to forget it was once supposed to be a place to park your car--now that everyone has a car, all of them parked on the street, it's hard to drive down the street, much less find a parking place. We've finally got most of our neighbors to leave the 2 parking spots in front of the building for us on Sun. and Wed.
I find the same thing happening with "privately built fellowship halls". In the beginning everyone remembers that they are NOT the work of this particular local church, but rather of various members. But as generations pass what they were supposed to be, like the Puerto Rican carport, is forgotten and not only does the church maintain them, but it expands or replaces them with a much larger one. After all, "we've always had a fellowship hall".