Bias: A preference or an inclination, especially one that inhibits impartial judgment.

Let’s say there are parties A, B and C. A and B offer something populist solutions Sa and Sb to very important problem X, C does not promise anything on it, but offers solution for less important problem Y (single issue party). If voter thinks that Sa and Sb are the only choices, they may choose A or B, because it feels right. If voter was informed that neither Sa, nor Sb solve the problem, but some other solution Sx not supported by any party would do it, party C could become a reasonable choice - at least you get something done this way. This would be impartial judgement. Wahl-O-Mat inhibits this scenario, so yes, it is biased, it is deceptive.