So, this text does not at all say that God intentionally withholds perception and understanding from anyone. It says that some suppress their nascent perception and understanding of parables because the parables message begins to challenge habitual behaviour they are unwilling to consider changing. even if changing will gain them forgiveness.
a person who is committed to rejecting the gospel can just as quickly reject a clear message as they can one obscured in metaphorical language.
the fact that the grammar indicates blind continuing to be blind rather than becoming blind does not indicate anything whatsoever about volition on their part ((that's 100% eisegesis 0% exegesis)) and it certainly does not by any means indicate God is attempting to open their eyes but failing because their willpower is stronger than His efforts.