Danni makes sense in this way
Ben and the other new school players wanted an old school player out. They wanted proof that there is no old school vs new school which mean that an old school player had to go.
The old school players did not have the numbers to vote out a new school player. Danni was targeting Parvarti this episode and Rob in the first episode. That means that she was not a reliable alliance member and had shown she was more willing to work with the new school players. As such, Danni was an easy person for Rob, Parvarti and Ethan to vote for.
While Rob and Parvarti are good targets for all the obvious reasons, they are better at challenges and are less likely to end up at Tribal with Rob and Parvarti then with Danni.
Danni's game play bites her in the ass.
What I don't get is the worry about losing challenges. In a season like this one the pre established relationships will help with alliance building/merging at the merge or during a tribe swap. It is not like these are strangers. A good number of them already know one another are a going to be willing to work outside the tribal lines. this season doesn't even have the hookey Heros vs Villians type label that makes idiots like JT, Colby, and Rupert believe that the "Heros" need to work together because they are the good guys, establishing a BS tribal division to die on.
I understand that going to Tribal is always risky but if you end up there, take out the end game threats. Rob or Parvarti should have gone home last night. Or, go to EoE.