"Really? A xin just 1v5'd? Wanna provide a replay? The Elo? How fed was xin? What was your and the enemy team comp? What items did you have? Did you properly CC him? Did you ignore him? Did you walk in one at a time, expecting him to let you kill him? Does walking in 1 after another really count as "1v5"? Did you position properly? Have you even played against a xin? have you even played league recently? Are you basing your entire opinion off of youtube/reddit videos?"
Nobody is going to write a dissertation about a single team fight so that they can be allowed to post a thread on the boards. If a champion is getting 1v5s or quadras/pentas easily then that's very likely a problem no matter how badly the fight was played by his enemy - most champions don't 1v5 just because people didn't adequately CC them.
I was watching a friend playing a game earlier where the Xin on his team was 2/6/5 before the fight, had Sated + tank items and got a quadra in a 4v5 (his Lulu mid wasn't there). He was against Rammus, Alistar, Cho, Draven and Kassadin. I didn't rewatch the fight ten different times, nor do I know precisely what items people had at the time, so I can't say if Rammus focused him enough, if Draven kited him well enough or if Cho missed his Rupture. What I can say is that a 2/6 tank generally doesn't walk out of a 4v5 team fight with a quadra.
Xin's stats are insane for champion.gg by the way. If he's doing well enough to be one of the best (even if not the best) junglers in Plat+ then he is absolutely retarded the further down you go from there. He is a champion with a permanently inflated low ELO win rate because people who play him are at an instant advantage compared to people who play champions with relevant mastery curves. If he's performing as strongly as he is on champion.gg then you know he needs gutting.
p.s. I've not made a single post complaining about Xin Zhao up until this point, nor have I lost a game to him. But people absolutely have the right to call him broken, because he is.