Thresh's itemization is now really bad.

He can't optimally build Redemption because he isn't an enchanter and doesn't benefit much from their items. He can't optimally build Knight's Vow because he's ranged and that nerfs it by 50% (unusable territory). He can't optimally build Zeke's Convergence because it just doesn't synergize with his Ultimate in any way.

That leaves him with Locket of the Iron Solari, which most meta junglers at high elo are building anyway. If he can't build any of the three items above, his build path is trash. Every other support can stack healing buff items and get a Redemption or they can combo together Knight's Vow and Locket of the Iron Solari.