Back in 2000, I voted for Nader, but even if all third parties had been purged from the ballot, it would have been Bush, not Gore who would have gotten my vote. I definitely wasn't voting for Gore that year and Bush never managed to seal the deal with me so I voted third party as a protest against two lackluster choices. The idea that all the voters for Stein and Nader are uberliberals who would have voted Democratic if there had been no Green Party is sheer nonsense. Not only that, but the presence of third parties likely made it a closer election than it otherwise would have been. Without Johnson and McMullin, Trump certainly would have gained New Hampshire and maybe Minnesota. Trump might have even won the popular vote, and at least kept the margin in the popular vote down to the size of his inauguration crowd.
Sure, not all Nader voters would've voted for Gore and not all Stein voters would've voted for Clinton. And yes, you're right about Johnson and McMullin, but I was simply responding to the idea that Stein voters didn't "make the difference", when in fact, her vote totals in the three states that mattered were greater than the D-R margin.