The Lord has inspired me -
One cannot "fellowship" in secret. It must be a sharing, a participation with others. In the case of prayer, in which we are told to go into our closet, it is a sharing of the bareing of the soul in prayer to God. In the case of sharing fellowship with the saints, it cannot be done without sharing the burdens of those who are in need. The same word translated "fellowship" in your excellent post, is also translated in other passages of scripture as "contribution, communication, communion, communicate, and distribution, all of which constitute a "fellowship" (koinonia = Strong's 2842) in one way or another.
Rom 15:26 For it hath pleased them of Macedonia and Achaia to make a certain CONTRIBUTION for the poor saints which are at Jerusalem.
1 Cor 10:16 The cup of blessing which we bless, is it not the COMMUNION of the blood of Christ? The bread which we break, is it not the COMMUNION of the body of Christ?
2 Cor 9:13 Whiles by the experiment of this ministration they glorify God for your professed subjection unto the gospel of Christ, and for [your] liberal DISTRIBUTION unto them, and unto all [men];
2 Cor 13:14 The grace of the Lord Jesus Christ, and the love of God, and the COMMUNION of the Holy Ghost, [be] with you all. Amen.
Phlm 1:6 That the COMMUNICATION of thy faith may become effectual by the acknowledging of every good thing which is in you in Christ Jesus.
Heb 13:16 But to do good and to COMMUNICATE forget not: for with such sacrifices God is well pleased.
Yours is an Excellent post, inspired indeed.