Someone downvoted you for spitting facts? Interesting. The two US parties are both right of centre, which gives an immediate imbalance. Small parties can have some bearing on their senior partners policies, like you say. I’m assuming Germany has local elections, mayoral elections etc. surely some of the smaller, more niche parties, pick up seats in those if they happen. Trends identified by smaller parties will get picked up by bigger parties, so they serve their worth there, too.