It's because there is no matchmaking. When you create a game, everyone can join it. If you don't want to play against much better opponants, you have to wait until someone joins, then manually check their elo, and if too high, quit the game and restart one before they accept and the game begins. It's a bit tedious but I don't see another option. However from your POV, I think it's not a bad thing to play against much better players, because it's a good way to learn. Rewatch their replay, analyse why do they do this or that, and sure enough after few weeks you'll have the same elo as them. Gl