Not that I've seen anyone argue otherwise (at least yet), but there weren't any third party spoilers in this year's presidential election. If we assume that Jill Stein supporters would have voted for Clinton had Stein not run, and that Gary Johnson and Evan McMullin would have voted for Trump had they not run, then Trump would have still won the election, and by a much wider margin (in the graph below, the two pairs of columns represent the actual and hypothetical electoral breakdowns, respectively). Interestingly, however, the outcome would have been different in several states (i.e., Colorado, Maine, Minnesota, New Hampshire, New Mexico, and Nevada).