Well, the threshold for establishing a new party is much, much higher than in proportional vote systems. Germany is about to establish its second new party since 1980 in order to address shortcomings of geriatric established parties which are increasingly uninterested in concerns of large parts of the population.
This doesn't even count the formation and establishment of an actual left wing party from parts of the social democrats and from the remainder of the East German communists.

A U.S. left winger in a right-leaning U.S. state sounds like a U.S. right winger in a U.S. left-leaning state, right?

Meanwhile a German gets to choose from an actual left winger in every state and an actual right winger in every state. Moreover, they're likely going to have a voice in parliament (and do their oversight job on the administration) as part of a minority caucus.

The system doesn't force them to adapt to the state's political culture; they rather remain quite true to their political orientation and the people get to choose.

This makes it easier for extremists to enter parliaments and get a forum for their noises, but said noises also allow to recognize their (lack of) qualities.