When they hear, they won’t understand.’ (Luke 8:9-10 NLT)
Why did Jesus tell parables? Parables or stories are easier to remember than facts and figures. Stories also carry a message HIs followers could hear and understand. Jesus enemies could hear but not understand, see but not believe. They saw Jesus do miracles but did not believe in Him. They heard Jesus speak but rejected His message.
The "secrets" of the Kingdom of God are open to all who see and believe. But they are hidden from those who reject Jesus, who deny God and refuse to believe. They put blinders on that keep them from seeing and believing.