Also, it's a mistake to think that the only result of voting is to produce the winner of the election. The margin matters also. A politician winning by a large margin (or even a majority) can claim a 'mandate'; one who only wins by a plurality will have more spirited opposition.
We've seen this in the most recent US election; imagine if small percentage of those who didn't vote in the solid blue states because their vote didn't matter (a refrain I've heard from many people) actually voted, and Trump swept the swing states but lost the popular vote. The entire political landscape would be different, and we might even have momentum in the coming years to abolish the Electoral College.
So if we are fans of liberal democracy, we should be doing everything in our power to structure the system to make people feel as though their voice and vote matters.