Well, anyone can ask you to renounce certain rights, and you can even agree, and courts can (and for certain rights have) rule that you cannot waive those right

Well, anyone can ask you to renounce certain rights, and you can even agree, and courts can (and for certain rights have) rule that you cannot waive those rights. Even if there's a right that is well known you cannot renounced, you can be asked to renounce it, and you can agree to do so, and still not lose the right. Arbitration can't completely remove access to the courts -- it can (and does) make it harder to get there. Case law for this sort of thing is always evolving, and so is statutory law. It's entirely possible for the courts to modify arbitration sufficiently to make the playing field more even.