if he can do that either you (i mean any player) and your team is playing bad or he's really fed
when he ult a target he will appear behind him (relatively to his initial position,if he was exactly on your right he will appear on your left),with the right timing you can throw your CCs here and stun him before he can do anything
also one of your teammates could get between you and him,heavily reducing his Q damage (it'll deal less than half damage)
if he goes away without consequences it means you either got too near and he ulted you without using his W as gap closer (so he used it as escape) or that you and your team got juked and missed everything
so returning on the original topic:
now I know I'm going to get barraged by "git guds" and other sorts of insults but I'm willing to say it. Zed is an issue.Zed is a major issue with us in the lower ranks and levels, especially with Smurf accounts using him against the low leveled players who are still trying to learn the game.
you can't blame a champion because you don't know how to play against him,also you talk about smurfs and in this case i have to say it it's a big issue,but the problem it's not zed but the fact that the player is smufing (so he's way better than you),they would be an issue with any champion
also making him a free target it's an absurd idea and it doesn't matter how strong he is it would make him unplayable and he would need inane compensations buffs that would make him even more a low elo stomper and even more useless in high elo
if he really need to be weaker at low ranks they should nerf his kit buff giving him compensations buffs that would affect him only in higher elos (stronger in high elo and weaker in low),your idea instead would do the contrary making him stronger in low elo (because all the compensations buff he'd need for this change) but weaker in high
also he would become unfun to play for his players because it would remove their outplay potential and instead make them a free target
it's not an healty change for both sides,making an ability countering the player that is using it is a bad concept