PoliEra tries to get back to normal by...rehashing third party myths:
In Michigan in 2016, Stein got ~50k votes and Trump won by ~10k votes. If Stein wasn't on the ballot, all it would have taken was 1 in 5 green party voters to vote for Clinton instead of staying home. I think the comparable margins in WI and PA were smaller but you get the idea.
Anecdotally, I don't think a single person I ever met who voted 3rd party would have vote for one of the major two parties if they were the only ones on the ballot.
But obviously, such anecdotal data and "logical reasoning" are beyond flawed as methodologies, which is why I asked if there was any study on this issue.
Is there any evidence that this matters?
It matters a lot for the kind of people that will vote no matter what out of civic duty, but don't like either candidate. Biden is winning that group handily in polling.
These people don't exist. Chikor is on the right track based on all knowledge about third party voters. They just don't vote otherwise.
It changes when there's a transcendent third party candidate like Perot, or when the major parties are shedding voters to "undecided" as was in 2016. Both Johnson AND Stein quintupled their support in 2016 not because of anything they did, they were the same candidates as four years earlier with only one party making a blatantly stronger effort at winning votes. (The Green Party is a mess, not an actual national party.)
Polling IS different, people POLL differently, more willing to "vote" third party since they understand it's a poll. Third options in polls always poll twice as high as in votes. Survey research shows this versus applied surveys across most all subfields not just politics. (i.e. Letting a person know it's a poll versus them participating in a controlled experiment.)
Plus the instinct to vote for a winner has been shown to be much stronger than to vote to send a message. (Even in multi-party systems!)