I am sure the Jews of Christ's day viewed it that way as well - but notice His solution to the problem in Mark 7
6 But He said to them, “Rightly did Isaiah prophesy about you hypocrites, as it is written:
‘This people honors Me with their lips,
But their heart is far away from Me.
7 And in vain do they worship Me,
Teaching as doctrines the commandments of men.’
8 Neglecting the commandment of God, you hold to the tradition of men.”
9 He was also saying to them, “You are experts at setting aside the commandment of God in order to keep your tradition. 10 For Moses said, ‘Honor your father and your mother’; and, ‘The one who speaks evil of father or mother, is certainly to be put to death’; 11 but you say, ‘If a person says to his father or his mother, whatever I have that would help you is Corban (that is, given to God),’ 12 you no longer allow him to do anything for his father or his mother; 13 thereby invalidating the word of God by your tradition which you have handed down; and you do many things such as that.”
Now obviously they want to reply "no we don't do anything wrong... everything we do is right - it is you who are wrong and we have our tradition on our side"
Yet Christ's sola scriptura method did work as we see in Acts 6:7
7 The word of God kept spreading; and the number of the disciples continued to increase greatly in Jerusalem, and a great many of the priests were becoming obedient to the faith.
Because the Bible shows it to be correct - just a in Mark 7 Jesus proves that the Jews were wrong by showing the Bible case for it... and not only could Christ's hearers see the point when He did so - but also in Acts 6:7 many of the priests came around on that as well.
And that is what you saw Christ saying in Mark 7.
God sends the Holy Spirit to 'Guide into all truth" as we see in John 16 - but He does not "mind zapp" people - each person must choose. Christ's method is the right one.
I always consider my view to see if it is in error - after all I am not infallible. But the Bible is and the Holy Spirit is as wel. God tells us to use Christ's method.
In Act 17:11 "They studied the scriptures to SEE IF those things spoken to them by the Apostle Paul - WERE SO" -- now these were NOT Christians doing it - they were people of the Jewish faith. Their own leaders were telling them that Paul was dead wrong. YET they had the ability "to read" and to see that Paul was in fact correct even though he was not strictly following their own religious leaders.
I understand. But the Bible shows us how it is done so we follow that method. A method that resulted in millions of Jews and 100's of millions of gentiles, pagans etc - rejecting their own leaders - and choosing Christianity.
1. The Bible is the work of the Holy Spirit - 2 Tim 3:16
2. Conviction of truth is the work of the Holy Spirit - John 16
3. Christ shows us how to use the sola scriptura method with opponents and Acts 6:7 shows that it works as does Acts 17:1-3