Bingo. That's why preachers / pastors are "sent" - that means they have both an internal calling to devote their life to explaining God's Word, but an external calling where competent, experienced peers can observe and evaluate that they are qualified for the undertaking.

Being earnest and enthusiastic is simply not enough. Just look at how much scripture twisting happens in online debates, bumper stickers, and highway billboards. The sheep need under-shepherds commissioned by the great Shepherd.