I'm unclear about why I'm being downvoted, since I'm just stating a fact.
Let's say there are two main political ideologies, kittens and puppies. There are two kitten candidates and one puppy candidate.
With a preferential voting system, if more people like kittens than puppies, a kitten will almost certainly win.
With an FPP system, the puppy will almost certainly win regardless of people's preference.
There are only two candidates in US elections because having a third candidate will almost certainly mean the least popular old codger will win.
The two-candidate presidential system is a consequence of a broken voting system.
Maybe someone can explain what I'm saying that incorrect.