What an excellent verse you have brought to this discussion. I don't recall thinking of this one in this context but your verse actually raises the whole bar. Not only is all doctrinal truth in the bible but life itself is completely dependent on the "scriptures/Word of God/word of Christ". Those who oppose sola scriptura can often be noticed opposing the bible itself if you pay attention and I'm sure they will not pay any attention to your post. But I sure noticed it.
Your quite right, but it is also a subtle attack on the Authority and person of the Lord Jesus Christ. In placing the Traditions of Men above the Scriptures, it is an attempt to place themselves in Authority above Christ and His Word.
It is an attempt to put themselves Above and Over believers and to tell them what to believe. Thus when Christ says "My sheep hear my voice", they believe it is their church and dismiss what Christ said "the voice of a stranger, they will not follow".
He also said "and they follow Me", therefore, a choice is presented, to follow their church or follow Christ, because they claim to be authoritative above His Word.
As I have noted previously, Pope Pius IX gave ALL SALVATION to Mary in 1849. The UBI PRIMAM has not been rescinded and is still posted on Catholic Sites. Therefore there really is no choice at all. Either you obey Piux IX and believe ALL your Salvation is by Mary, or you Follow Christ Alone.