Like I said, she's definitely not a medal favourite, but "she hasn't been top-5 in any race this year" is rather underselling her qualities/performances
Since January, every single race she has done from the Deakin University Elite Women's Road Race on (where she finished a more than excellent 9th) has been a big one-day World Tour race, none of those smaller .1 races in between. A very respectable 25th in a tough Strade Bianche, after being in the breakaway for a long time, 11th in the Trofeo Alfredo Binda, 9th in De Panne, 13th in Gent-Wevelgem and probably the best of all, 10th in Roubaix after very much being part of the main part of the race at the end. Her weakest race in the past two months was a 23rd in the Tour of Flanders, of all places. That being one's worst result says a lot (in a good sense).
In her entire pre-Olympic career, Anna Kiesenhofer had basically accomplished nothing remotely near to what Pienaar has shown in the past three months alone. Again: that does not make her the (or a) favourite, obviously, but in road racing weird things can happen and she is definitely a contender to keep an eye on, instead of one of the default 'exotic nation riders' who we often see in the first lead group of the world championships.