I’m not very well-versed on all this but it seems
First Past The Post
Benefits the two parties in a two-party duopoly system like that of the US. Boom or bust, black or white. When the party in power pisses you off you vote their competitor even if holding your nose.
Seems like there must be a better way, maybe just not as good for those who prefer shooting fish in a barrel
But when you have a problem, you complain to your representative that represents your area and knows all the details. That’s a powerful thing.
In the UK at least there are a lot of seats that are swung by those holding them rather than their party.