This is exactly what I was thinking! As I read his quote I was reminded of the “teach to know” part of the “teach to know, share to grow” principle you shared from 2 Tim 2:2 in this video. It is definitely something that has held true for me.
That said, there have been sermons that have been immediately and deeply convicting or encouraging, that have shaped my heart, thoughts, and actions. Listening to sermons definitely draws me closer to Christ as I am reminded of His goodness, love, and justice and am called toward a greater faithfulness in my response to Him.
I think preparing to understand and teach the Bible makes me slow down with the Scripture though and helps me to think through many questions and difficult areas to understand that I might miss otherwise. This depth of time, together with the community component of teaching, really helps me to see more of who God is on a more consistent, and often more lasting, basis than sermons.
I think even above preparation and teaching in impact for me though, has been discipleship - intentionally opening my life to, going through scripture with, and accepting both correction and encouragement from an older and wiser Christian.