I don't know why they responded that way, but here's how I would've responded.puckerman said:I naturally reasoned that with the top-two law the Libertarians could actually make an effort to get into the top two. But this wasn't on their minds. They just wanted to make sure they were on the ballot in the general election. They didn't seem to be interested in actually trying to win the election.
The main point of Libertarian campaigns isn't to get elected (since the system tends to be rigged to prevent that from ever happening; if the major parties wanted to give Libertarians a chance to get elected, they would have put in place proportional representation), but rather to raise awareness of libertarian ideas.
The endgame might be to elect Libertarians at some point in the future, or influence the major parties in a libertarian direction, or involve the people in civil disobedience or armed revolution that would overthrow the government. But we're not at the endgame yet.
(We don't necessarily have to use elections as an educational venue, by the way. Many libertarians don't; some prefer to become economics professors, for instance, since they figure they can reach more young people that way. Civil disobedience can be another method of outreach, although I personally haven't had a lot of success with it yet, despite devoting 46 months of my life to it.)
One might argue, "There actually are a lot of libertarians out there, but they vote for the two major parties because they don't want to waste their votes." The spoiler effect is more noticeable under a plurality system, but it would still exist in a top-two system.
Let's suppose your first preference is Johnson and your second preference is Trump. In the first round of voting, you might vote for Johnson if you figure he's only going to get a few percent. After all, in the second round, Johnson will be eliminated and then you can switch your vote to Trump. You will have registered your support for Johnson without "throwing away" your vote.
What happens, though, if Johnson and Hillary are the two top voter-getters? If Hillary defeats Johnson in the second round, then you're actually worse off than if Trump had made it to the second round and defeated Hillary. So the problem of Johnson being a spoiler still potentially exists.
Proportional representation would give minor parties more influence, but then the problem might arise that they get TOO much influence. The Communists or Greens, for instance, could tell the other parties, "You better accede to our demands or we won't form a coalition with you."
Arrow's impossibility theorem says that there actually is no good electoral system. Or at least, there's no perfect electoral system.
Top-two might not be such a bad system, if people actually paid attention to the primaries. We're lucky if they even pay attention to the general election, though.