I would have to strongly disagree with this. I have always been a big supporter of third party candidates and I believe voting for them is where your vote can be most effective. The third parties rely on how many votes they get so that they can be on the ballot in the next election without having to petition for it.
Here in NY, Cuomo was a shoe-in for governor against kooky Carl Paladino. There was no worry of taking votes from him if you voted for one of the very colorful third party candidates we had representing, so I threw my vote to Howie Hawkins of the Green Party. The Greenies got the amount of votes they needed for that race so that next time around they can automatically include a gubernatorial candidate and I feel good that I played a small role in that. Actually, all of the 3rd partiers got a surprisingly large number of votes in that specific election and I see it as a fantastic thing.
Even if the third parties don’t get much of anywhere, ignoring them or considering them a waste of time is doing a disservice to yourself and your fellow citizens, especially with the extreme stances the “big 2” take on all the issues now. We need a larger array of candidate choices to reflect the varied populations being represented and this is the way to do it.