First off, anyone who wants to reject Hillary’s shocking level of corruption but doesn’t want to vote for Trump because the media says he’s a big meanie or whatever, I heartily encourage you to vote for Jill Stein. Look at her spray paining bulldozers! She believes in the environment! She will stop global warming!
Looking back, Nader took almost 3% of the vote, that waws all taken from Gore and that year was so close, those number could well have made a difference.
I would say that Nader had less in common with the DNC back then, than Jill Stein honestly has now. The Dems have made a hard left turn since 2000. Jill Stein strikes me as a typical bleeding heart guilty white liberal cat lady and I think she would fight right into the mainstream DNC if she didn’t call herself “Green”.
I’m not saying 3rd parties are always controlled by the major parties, I just think that in this particular election the Green party and to a larger extent the Libertarian party are just meant to pull anti-establishment voters from Trump. I don’t know if the DNC is directly involved, but wikileaks has shown us that they are directly involved in a lot of dirty tricks.
That's the Bernie Sanders factor. Clinton is running farther to the left than she did in 2008, so the differences between Greens and Democrats are less than they may have been in previous years.
Also, Stein isn't much of a draw. A stronger candidate might really cut into the Democrats' percentage. As it is, she's not that relevant -- sort of a boutique candidate.
You're not wrong to suspect that she's window dressing more than anything else. Still, she will take more voters away from Clinton than from Trump, and that won't help the DNC.