Third parties help the democrats because the biggest third party is more right-aligned.
In Michigan Gary Johnson got 172,136 votes, in Pennsylvania he got 146,715, and in Wisconsin he got 106,674. If all Greens voted Clinton and all Libertarians voted Trump then New Mexico would’ve only been won by Clinton with around 1,000 votes, Colorado would’ve also been nearly Trump. Nevada, New Hampshire, and Minnesota would’ve been won by Trump. Maine might’ve gone majority Trump.