I'm not sure how the survey was phrased to participants, but to me a "hobby" is a regular thing someone does, as their way to pass the time/have fun. I've smoked before and have no problem with it, but I do think I would find it less attractive for it to be someone's hobby, as opposed to an occasional social thing they do.

Similarly I have no problem with people watching porn, but if it's gone far enough for it to be considered their hobby, then that is less attractive to me, which also matches the chart.

I might be misunderstanding the word hobby, but so might many of the survey participants.