To bring this to a close, the institutional church is highly necessary if our goal is for Christians to come together. If people are going to come together, they must have an organization of some sort. An institution is really just an organization plus time. Institutions are inevitable in human society. If Christians are called to love one another, then they will inevitably form institutions. If they take the Bible seriously, they will set up boundaries of fellowship.
So, why not simply form your own organization based on what you think the Scripture says? At times, like during the Reformation, this may be necessary. However, even in the Reformation, the Reformers sought to look to the best of the past in order to learn how to put together their institutions. Theoretically, you may be able to build a better institution, but knowing you (whoever you are), probably not. The likelihood is that if you start from scratch, you will still build an institution. It will just be a very bad one.