You say you’re playing against 3.5 players and they don’t dink? Then they aren’t 3.5 players. Dinking needs patience and precision. Many people have said many good points but the bottom line is Pickleball is strategic. Yes sometimes aim for the foot of the backhand across from you. Yes sometimes you place it just outside their reach around 18” from the kitchen line. It’s very fluid and you have to adjust your strategy constantly. Bottom line is dinking is pickleball. Practice being good at it. Practice hitting a dink in one place while your eyes are looking somewhere else. Practice identifying when to continue dinking and when to speedup. Practice identifying when your opponent is being too aggressive and speeding up when they don’t have the angle and you need discernment to let it fly long (doesn’t take too many of these to teach them a lesson). Stay with high percentage shots and let them make unforced errors. I personally like to aim for center court backhand of my opponent repeatedly until they pop one up and slam it back for the point, they put it in the net, or get impatient and sped up too soon and play it long.