In terms of quality it might be much more difficult for Darmstadt to beat Dortmund and I also don't see the match ending in a draw with the quality of players available. So realistically I see Darmstadt's chances in the next three matches will be much more difficult to get points because they face much stronger teams.
You are right on that , that it will be difficult for Darmstadt to get an or any point out of the next games.
But on the other hand we have seen that Dortmund making some bad surprises , specially against such teams we think they win them.
With what Dortmund has played some matches the last weeks its possible to see some unexpected result.
My bet there will be for sure on the win for BVB.
Overall, maybe I will also say the same thing as you regarding this match, which if we look in terms of standings statistics, it shows that Dortmund's position is far above, while Darmstadt themselves are at the bottom of the standings in the sense that there is absolutely nothing to expect from them for this season or their overall appearance is very bad so of course if we look at a glance, it is clear that Dortmund are more favored in this match.
However, it is quite reasonable as you say that if we look back at Dortmund's last few matches I think there is absolutely nothing satisfying about their performance, very different from usual. The draws against Mainz and Augsburg are a hot topic of conversation where both of these teams are far below Dortmund but Dortmund can only get a draw in both of these matches. So I think it's only natural that there are some speculations and assumptions that doubt Dortmund in the match against Darmstadt, unexpected results or even worse than the previous two matches are still possible.