Restricting the number of votes each voter can cast causes the same problems as FPTP, the so called "spoiler effect". Ideally a voting system tries to get infor

Restricting the number of votes each voter can cast causes the same problems as FPTP, the so called "spoiler effect". Ideally a voting system tries to get information from each voter about their opinion of each candidate. Why prematurely throw away most of that information? However, a system similar enough to your example has been used for years by the Quakers, where each voter gives a score of +1, 0, or -1 to each option/candidate. The difference here is that you can give +1 to multiple candidates, and -1 to multiple candidates. Giving your opinion on one candidate in no way limits your ability to give opinion on other candidates.