Your church uses a website and a Facebook page, so why can another church have a fellowship hall?
I'm not even saying I want to have or like having a fellowship hall, but given your stance that the Bible does not specifically provide for it, why do you have a website and email for your church? Also, why do you have a Facebook page? Is not a Facebook page, if used the way Facebook is intended to be used, extremely similar to a 'fellowship hall'?
Thanks for your time.
Whenever a command is given, it sets limits. The command excludes certain things and includes others. It is much like the Venn diagrams we did in math classes. Some commands overlap, such as both individuals and the church offering up worship to God.
The church is commanded to spread the gospel. "So that the manifold wisdom of God might now be made known through the church to the rulers and the authorities in the heavenly places" (Ephesians 3:10). This spreading of the Gospel can be done in a variety of ways: verbal or written; it is the communication that is being emphasized. Thus, the church supports preaching and teaching of the message in sermons, preaching in other areas of the world, Bible classes, articles, etc. The website is one aspect of this, as is the church's Facebook page. All you will find on either medium are teachings about the Bible and on rare occasions announcements about changes to the assembly times.
Like most congregations, we have a mailbox, a phone, as well as email to communicate with people. These are used to set up Bible studies and hold Bible studies with people I cannot physically be present with. But these are still being used under the command to spread the gospel.
Fellowship halls are used for socializing, especially for people eating together. Having common meals together is something authorized by God for individual Christians (Acts 2:46), but where is the command that it is required of the church to provide a facility for social gatherings? I can see in Acts 6 that the church provided food for widows and I Timothy 5 tells us that it was restricted to only certain widows who had no other family to care for them. None of these cover the typical use of a fellowship hall.
Notice also that your line of reasoning doesn't work. You are trying to find an exception to one rule so as to claim there can be exceptions to all rules.