No, it's definitely a FPTP failure. If you have progressive third party candidate who mostly attracts voters who would otherwise have voted Democrat, it splits the vote. Even if the majority of people voted for either the third party or the Democrat candidate (let's say 30% each), the Republican candidate would get win even with 60% of people not wanting them.

I suspect you're thinking of people being afraid to vote third party and thus dooming the third party to lose, but the fallacy of that is assuming that everyone would genuinely vote for the third party over other candidates, which isn't the case. Articles like the one we're commenting on are only pointing out the most common belief.