A reason Shonee and Fenella have some popularity I think is because they are underdogs and while you are used to bro alliances on Survivor you don't get female duos that often.
I know Shonee is getting very confident confessionals shown which don't appear justified, but I see that as part of Survivor. The same with Benji really. It's how the show developed in the US and that has influenced the way the game is played everywhere else. Once you've seen enough US Survivor you just get used to this kind of approach which can seem delusional/egotistical at first but once you see people get to the end with that kind of edit and having moves that shape the game you just end up accepting that that kind of confidence can work in some storylines. And with deception and breaking promises all end of being part of the game as well Survivor ends up being very different to some other reality shows. We even had Shane suddenly saying she will be a snake and that she has power of a sort. I'm not too convinced on that but the story as it develops will prove it or not. Survivor is ultimately a power struggle of egos, there are alliances but they are often there to be broken eventually.