I think you've made a straw man out of what's been said here. I'm not arguing Lorewalker Cho works in every situation, just like a mill deck doesn't work against every single deck. I'm not even arguing that it's a consistent card. Yes, this card has no board presence, yes, people can kill it for free if it is unprotected.
There is a class of cards in this game that will have extreme problems killing you. If your opponent gets a power word shield, a healing touch, a divine spirit, a tree of life, the situations in which they kill you with those cards are so remote, they will land you on a trolden video. Moonfire likewise, does such nominal damage that unless you're staring down a tempo mage or a Malylock, giving your opponent one is essentially giving him a "Congrats, you can do one damage next turn" card.
Your opponent has a deck of thirty cards that, in one way or another, are designed to kill you. It may be with some bloated creature like Tirion Fordring, it may be a spell that does 6 damage like fireball.
In a mill deck, the objective is always to fill up the opponent's hand. The big mill combo is Coldlight-Brewmaster-Coldlight, or Coldlight-shadowstep-Coldlight, which nets you 4 drawn cards. What I'm trying to state is Cho can match that amount of card draw, by artificially inserting Moonfire (a spell that uniquely DOESN'T HAVE A COST) and naturalizes (that has an extremely small cost, with a HUGE benefit to you if cast back at you, whether Cho is on the board or not).
So, if Cho's on the board, you cast moon fire, then naturalize, and then cold light-brewmaster-cold light. You've essentially filled up his hand and made him draw 8 different things. I'm not arguing that that's phenomenal against a face hunter who has two cards so you give him a complete hand. I AM arguing that it is phenomenal against a control deck that's holding on to 7 cards, so he draws 3 and then 5 of his cards, 1/6 of his deck, is burned. Burn the right cards, and that can bring an entire deck crashing down. Freeze mages are a joke without Alex, I also find myself laughing when a Thaddius component goes up in smoke. The reason Blizzard doesn't constantly print mill cards is because if the play style gets too efficient, or out of hand, it'll be OP, because BURNING CARDS so that you NEVER HAVE TO USE RESOURCES TO DEAL WITH THEM IN THE FIRST PLACE is VASTLY SUPERIOR to USING YOUR RESOURCES to deal with threats.
The strategy's ridiculous is it? That's why me and people like me play it. It's entertaining, in a game I play for entertainment. I don't care if Reynad doesn't use it to beat Strifecro in the world finals, or even if it loses me half of my games and keeps me far away from legend. If you don't believe it can work, check out Wowhobbs on Youtube. He plays a priest, using buff cards and faceless manipulators to essentially protect Cho and amplify his effects. The usual result is he floods his opponent's hands with cards that can't be used to kill anything on the board, before he goes in for the kill with an inner fire or transforms the millions of power word shields that get shifted back and forth into legendaries with an Elise.