In a single-winner election, why would you think that? The "minority extremist parties" are going to lose anyway, so why not try to let people vote more honestl

In a single-winner election, why would you think that? The "minority extremist parties" are going to lose anyway, so why not try to let people vote more honestly, so that they don't need to strategize? For example, I don't want people who naively vote Green to end up wasting their vote just because they don't know how the voting system works.