[armagon]

Widely used voting systems converge on two parties. The worst offender is the first-past-the-post system. Instant-run-off voting is better, but still converges on two parties.

Wish I had a good citation for you, but I do have an try-it-yourself guide on voting systems to link to: https://ncase.me/ballot/

[valarauko]

India has FPTP as well, where the tendency has usually been in the opposite direction - splitting parties.