As someone from a small European country, it still seems weird to me that you need to encourage people to please go vote. Because where I live basically everyone is required by law to show up at a voting station(but not required to vote, you don't have to cast a valid vote just show up). While it is off course not the perfect system, I think it is still better than hoping non extremists show up to vote. It probably also helps that we don't have a 2 but about 8 party system.
While there are many parts to consider, and everyone loves to make fun of Republicans for the whole "muh freedoms" thing, ironically, I want to point out that part of truly being free is the freedom to not be required to vote or even show up.
That said, it's stupid as fuck and everyone that can should absolutely be there casting their vote.
There's a number of reasons for this like the electoral college and voter suppression.
The electoral college basically means that all of a states votes go to the winner of that state. If you're casting a minority vote in that state it's very easy for it to not affect the outcome in any way, unlike if the winner was determined by popular vote where every vote mattered. This is also why we see presidents elected even though they receive less votes, which further undermines the system.
Then there is rampant voter suppression, usually in Republican controlled areas. There is a strong correlation between more people voting and Democrats getting elected so Republicans try to make it as difficult as possible for people to vote, especially people who are likely to vote Democrat. So they pass voter ID laws, restrict mail-in voting, close polling places and shorten polling hours. In these areas people might have to spend hours traveling to a polling place only to stand in line for more hours before they can cast their vote.
Add in that voting takes place on a work day when it should probably be a national holiday, the two party system, and other stuff and it's easy for people to feel lukewarm about voting.
There isn’t a two party system. It is only bipartisan because such a system generally reduces to two in a polarized and popularity system. even though through state or province they will often pick a 3rd party, sometimes those people will decide that their 3rd party doesn’t have a chance they just do not want to see an opposing party win so they’ll vote via popularity vote instead of their preferred 3rd or 4th party. They settle. And I’m not sure a rating system would reduce the chance of that happening either.