Why posit a false concept of what Sola Scriptura is?
It's the only option they have.
Jesus clearly thought that Scripture alone was enough.
He quoted it at the enemy to counter the temptations, and constantly stated that *It is written....* and considered Scripture authoritative for determining truth claim.
Matthew 22:29 But Jesus answered them, “You are wrong, because you know neither the Scriptures nor the power of God.
Mark 12:24 Jesus said to them, “Is this not the reason you are wrong, because you know neither the Scriptures nor the power of God?
John 2:22 When therefore he was raised from the dead, his disciples remembered that he had said this, and they believed the Scripture and the word that Jesus had spoken.
John 10:35 If he called them gods to whom the word of God came—and Scripture cannot be broken—
Luke 24:27 And beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself.
Luke 24:32 They said to each other, “Did not our hearts burn within us while he talked to us on the road, while he opened to us the Scriptures?”
Luke 24:45 Then he opened their minds to understand the Scriptures,