If a candidate is preferred by more than 50% of the voters, but doesn't win, then the voting system is rigged. In that case the voting system is not important.
But we have formal voting systems to cover the common case where no candidate is thought to be the best by 50% of voters.
* A rigged system can be justified in some circumstances. If the population contains a cohesive minority, such as Catholics in Northern Ireland is could be acceptable to rig it to ensure that the minority gets some seats in government. But strictly speaking that is more about how the overall chamber is selected than individual seats.
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[ I have another quibble about your statement - I have to assume that you meant 50% of the people voting for that seat. ]
I Disagree
If a candidate is preferred by more than 50% of the voters, but doesn't win, then the voting system is rigged. In that case the voting system is not important.
But we have formal voting systems to cover the common case where no candidate is thought to be the best by 50% of voters.
* A rigged system can be justified in some circumstances.
If the population contains a cohesive minority, such as Catholics in Northern Ireland is could be acceptable to rig it to ensure that the minority gets some seats in government.
But strictly speaking that is more about how the overall chamber is selected than individual seats.
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[ I have another quibble about your statement -
I have to assume that you meant 50% of the people voting for that seat. ]