Therefore, it can't possibly affect your chances to win like it does in dice. It is 50/50 in terms of winning or losing for two players before the cards have been dealt (if we discard the ramifications of skill and expertise from the equation)
A house edge does not only mean a certain amount of advantage of the casino over the player in terms of winning chance. In a dice game, your winning chance could also be set at 50%, which means the dice site does not have any amount of edge over you in winning probability. That means that "It is 50/50 in terms of winning or losing" just the same. But the house edge is in the payout or winning prize. Your chance of winning against the house may be 50:50 but your winning prize will not be x2. That means the house still has the edge over you.
In a poker game, you are playing against another player but a portion of the winning will go to the house. In which case, the house wins every time a game ends, regardless of who wins. This is also the same rule that applies over sports betting. That may not be aptly called house edge but it is somehow similar to that.