I mean you are only viewing the "way" we select teams based on the way its done now. In the future, the team selection could vary quite a bit and that would change a lot. For instance, draft mode where you pick a summoner from a list of available choices. Or another would be a nullify mode, where you can block the other summoners available like the do in brawls.

My point is that there are lots of possibilities and one day hopefully we will have many ways to use our cards!