1: Democracy is an ideal, not necessarily a reality. In its perfect form, popular will causes changes in policy, but if arguments over procedure and process have taught us anything, it’s that there is nowhere near a consensus regarding what that perfect form is.
2: Democracy is based on consensus, and policy resulting from the democratic process is designed not to be perfect for anyone, because that simply isn’t possible: worldviews are subjective and no single person’s idea of good and evil matches any other person’s view of good and evil. That means public policy is designed to be a “good enough” fit for as many people as possible, even if it alienates some. Just because you happen to oppose that public policy doesn’t mean everyone else does, and even if the popular will happens to be grasping, self-serving, and short-sighted, it’s still where the state derives its legitimacy from.
If the four “bourgeois parties” are unassailable in Germany (and it seems like they are, since 13% is still a pretty small minority), then that’s because the popular will has demanded it. If the majority of people approve of the current political establishment, the current political establishment will continue, because that’s where they derive their legitimacy.
The problem you seem to be facing is that any form of consensus governance isn’t about individuals as it is about the abstract concept of “the people”. So long as democratic norms are maintained, “the people” have the right to redress and change, not any single individual, because the second an individual imposes their own morality on a system which can only function effectively as a collective, you no longer have a political consensus, but one person having to force their worldview on everyone else.