> The significance of a vote for a candidate that cannot win is zero.
That isnt the reality, and is a oversimplification to game the system.
You can argue it has a much LOWER chance of winning. but not 0... Based on historical data the chance of a third-party candidate winning an election or coming in second place (and thus becoming a primary party in the future) in any one year is ~7% , something like 3% for the chance of actually winning.
That isnt 0, it is low. But pushing for something with a low chance, that is far better for everyone, and having 50x the impact in doing so Is a very good trade IMO.
Also, what is the point of voting for a primary candidate when your chance of your vote having **any** meaning at all is 0.00000001%.. not voting would have no impact of any kind, so why bother, where voting third party has a 50x impact and even when loosing that impact has quantifiable gains (unlike with the major party).