The United States is unique in the sense no other country in the world has an electoral system like ours. Not only from a federal perspective with the electoral college, but amongst municipalities, county, state, and congressional elections one sees the effects of the winner take all system we embody. If you have no knowledge of how elections work in the US here is the simplest way it can be explained. The idea of the winner take all system is that if you win a district or a state or whatever body of constituents it may be, then you take all of those electoral votes. Electoral votes accumulate and once a certain threshold is broken by a candidate then they are declared the winner. The issue that most people have with this system is the fact that all the votes that are for the loser, in that specified body of voters, is neglected and in essence are then given to the winner.
Here is why this system is outdated and needs to urgent reform.
It is inherently undemocratic
The most common argument against the winner take all system is that it undermines the people's votes and hence contradicts the principles of democracy. Which is evident from a first glance, primary examples can be seen throughout history such as in the 2000 presidential election. Presidential candidate Al Gore had won the popular vote and lost by the slimmest of margins as the entire fate of the election came down to the state of Florida and more specifically a single county.
Then-president-elect George W. Bush had literally won the presidency based off a state in which he won by a few thousand votes, but those few thousand votes allowed for him to acquire the electoral votes in Florida and cancel out the millions that voted for Gore. The entire idea that almost half of a state of people can go out and vote for a candidate but then have their vote essentially ignored and given to the opposing candidate is appalling. The United States is founded in this principle of giving power to the people but how is that being accomplished when every election cycle we see millions ignored with no voice.
It creates a two-party system
The latter of the two reasons revolves around the notion that the United States is completely dominated by two political parties. Whilst third parties do play a role by highlighting issues and taking away voters from potential candidates, they have absolutely no representation. And this is something that is impossible to change as the democratic party and the GOP have a surplus of resources that allow for them to be the only notable parties in the US.
Moreover, this notability is crucial because a party absolutely needs to win the entirety of a district or state in order to obtain any representation and no third party can sufficiently accomplish that goal. As a result, American citizens can only choose between the two major parties, hence creating polarizing ideologies and a group of ostracized voters who did not fit into this categories.
So now you have a political realm filled with minimal bipartisanship and apathetic citizens because they do not feel they are being represented. Additionally, those who do not associate with these parties cannot achieve fair representation as they can not even vote in the primaries. Which is why you find situations like the 2016 election in which people are talking about picking between the lesser of the two because of the minuscule percentage of people who vote in primaries. In order to have a thriving democracy, a country needs multiple political parties as it allows for adequate representation and it gives a greater incentive for parties to form coalitions and progress national interests from a more bipartisan perspective.