The problem isn’t that such candidates would never accomplish anything let alone get elected due to the insurmountable amount of resistance from so many incumbents with a vested interest in that not happening, ever.
One of the biggest problem of a two-party system is that the two parties are thoroughly captured by lobbyists.
In a PR system, fresh parties do arise over election cycles, and it takes some time for them to be thoroughly infested. These can then push for some reforms that threaten entrenched interests, and sometimes succeed.
