It's not an error in understanding. Opponent plays Tirion, and I am top decking with nothing left. It's not an error in play. Sometimes you don't have options. Sometimes I have 8 1-mana cards in my Zoo deck, and I don't get a single goddamn card with less than 3 mana in my draw even after pulling a mulligan on the whole hand. It's not my fault, and there are no other choices I can make when my Shaman opponent already has 3 minions on the board by the time I can play one, and I die by turn 6. It just happens, and it's ridiculous to pretend otherwise - we've all been there, and Arena isn't any different.
If both players play the board equally well through the first half-dozen turns, one player having good high-mana legendary drops absolutely seals the deal in this game. Even when people here draft decks and get lucky hands, people say things like "That's a 12-win deck", and they're right, because they can recognize that someone got blessed by RNGesus in this game. I really wish you would stop pretending this game doesn't have the flaws it has. This is the same as when you said spending money doesn't give you an advantage in this game, and you stopped posting when I had clearly won that argument as well.
I don't plan on continuing this conversation with you further, based on what I have said above. You are welcome to respond as you like.