That’s all true, by voting for minor parties you do entice the established parties to grab some of their policies. This does not address the fact that in FPTP a fractured ideology loses because of the spoiler effect. If you get 5 parties with 10% vote share. Dems on 20% and Republicans on 30% it’s a Republican win even though their ideology doesn’t resonate with 70% of voters.

You need tactical voting to get the majority of seats in this case also and in a situation where everyone would vote tactically against Republicans they will be pro voter reform since it’ll reduce the power of a united right wing.