Nefermandias
Hero
3d6 makes the result so predictable that we might as well get rid of the check and just have the DM decide on the outcome.If anything, I would have preferred the game use the 3d6 bell curve instead of the d20 for the core mechanic. 3d6 emphasizes your ability modifier and proficiency bonus over dumb luck on the roll.
There's nothing worse than making an important Stealth roll with a +8 bonus, only to roll a 2 on the d20. The 3d6 makes rolls around 10 or 11 far more likely, so your modifier makes a bigger difference while still leaving some variation for random events/circumstances.