there's no such thing as "acceptable" or not, there are just utilities and _relative_ satisfaction. you want to get the most satisfaction possible from the options you have.

https://www.rangevoting.org/RVstrat6

approval voting is insanely good at this.

https://www.rangevoting.org/BayRegsFig

What does what look like? Approval voting? The unacceptable (usually extreme) candidates fail to get votes and so get booted out of office, with their places taken by more moderate, common-sense candidates.

FPTP, particularly with partisan primaries, has the misfeature that you need to rally the base in order to win the crowded primary field. This leaves only extremist candidates heading toward the general election. In a country like the U.S. where voting is not compulsory, this turns off the moderate electorate, who are forced to choose between two extreme candidates that both seem batshit crazy, and encourages them to stay home.