I’m sorry, but that’s not even close to how democracy in general works.
I’ve lived, worked and voted in The Netherlands where vote is proportional and there the “useful vote” (or as it should be better called “negative vote” as people vote against the other candidate rather than for a candidate) does not exist at all.
I’ve also lived and voted in other coutries of Europe with different systems and the Dutch one is one of the best and that certainly gets reflected in their politics (those of consensus, not partisanship) and outcomes and the only one which is as bad as the US is the British one (in fact, with a Monarch with real power and an unellected 2nd House, it’s probably less democractic than the US system, though at least their uninominal electoral circles aren’t as large as in the US)
(All those countries were EU countries at the time, hence why I could vote in all of them, though in some only in Local Elections and for the EU Parliament)
The US is a not a Democracy, it’s this wierd Power Duopoly system with a near-symbolic vote sitting between a Power Monopoly (i.e. Dictatorship) and real Democracy.
Do not confuse your ignorance when it comes to voting systems with what is maybe one of the most visible effects of anti-democratic voting systems being “how democracy in general works”. Not! Even! Close!