These personal studies always seem to go this route: The person got all their understanding of this
(and any subject can be inserted here) Biblical subject by reading Scripture only. Any other supplemental resources are always non-biblical sources. Unnamed. Never are any other biblical sources employed; that would be sacrilegious apparently. And the person making the claim wouldn't appear as spiritual, either.
Reminds me of when I made a visit to a home, and before the door was opened the man of the house ran down the hall into the living room, grabbed a book to read and had someone open the door so that when we came in it appeared he was spiritually engaged. lolzzzzzzzzzzz...
So many today want to appear as if everything they believe came from Scripture only, and from God speaking to them personally, avoiding all other teachers as if to avoid them makes them a spiritual maverick.
"You need no man to teach you..." (1 John 2:27) is ripped out of context and pitted against the teaching of
Ephesians 4:11ff concerning God's decree and biblical structure of teachers and pastors who are to teach and equip the saints.
The thing is God knows we need one another, thus He structured the church to accommodate and facilitate this need. Those spiritual mavericks who get everything personally from God alone, and
"don't need man to teach them" need to submit to God's order. It is actually a rebellion to this order and to God Himself.
The sooner the church can dispel this attitude and these types, the better. BTW, most of these whom I know don't even go to church. They "love Jesus" but hate His wife. Jesus isn't buying that.