This is a very biased query...
Did you think even once of praising Rubina when she did the task in Harsh segment in WKW so well?
One of the initial tasks in BB14 - where she had to show herself confused - that too she had done wonderfully but she wasn't declared the winner
The task where she danced on Maiyya Maiyya- everyone agreed that she danced brilliantly, yet she wasn't chosen as the winner even against Kavita.
These are just some instances of how BigBoss victories are not based on skillset.
In the Chyawanprash task, Rubina could have been the best orator or salesperson but she wouldn't have won because the decision wasn't being based on Rahul or Rubina's skills but rather the housemates relationships with each other. No matter how well Rubina would have performed, neither Rakhi nor Devo would have chosen her. Rakhi even said that she didn't like Rahul's product but was choosing him..so how can one even blame Rubina for losing that task??