The system isn’t designed to be a two-party system, but no matter how many parties there actually are are (in the US, there are actually more than a dozen active parties), FPTP voting inevitably results in only 2 being viable.
This will not change unless a different voting method is implemented.
This video explains it quite well:
Minority Rule: First Past the Post Voting by CP Grey.
The system isn’t designed to be a two-party system, but no matter how many parties there actually are are (in the US, there are actually more than a dozen active parties), FPTP voting inevitably results in only 2 being viable.
This will not change unless a different voting method is implemented.