I remember the same question arising in my mind, at least thirty years ago, when writing in French the tract "On Worship." There is one thing which may facilitate your inquiry. John's writings always refer to the individual. Chapter 4 shows that individual worship is recognized. But if this was in intentional separation from all saints, it would be another thing. Love to all the saints is a necessary ingredient in the heart's going up to God. But worship together has a distinct and peculiar character, because there is Christ's promise to be there. "In the midst of the church will I sing praise unto thee." But I do not doubt that if I am alone I can worship God alone. Still scripture is full of joint worship, and so it will be in heaven.
But in an assembly I should think it an unhappy thing for one to set himself apart as superior to others. Our part is to esteem others better than ourselves, and whereto we have already attained, to mind the same thing. If it is something that positively grieved the Spirit, it is another thing. I cannot in Spirit have communion with what is contrary to the Spirit. But while I admit a low estate of soul will be painful to a spiritually-minded person, yet in the case you put, the person has not learned to esteem others better than themselves. "Let each" it is said.
London, February 5th.