A lot of Helio's winning backlash (which seems minimal now) was for a few reasons.
He was the 4th male in a row to win having Kelly only as the sole female winner by season 5, in a season with the likes of Mel B, Jennie Garth, and Sabrina Bryan. We as a audience assumed as charming as he was, he was destined for a 3rd place or runner up slot.
As disappointing as Mel B's freestyle was we didn't know the true impact of the freestyle or the charming male vote, and we assumed with how good Mel was and how great her and Maks were together, most assumed from her multiple perfect scores and a woman not winning that she was going to win and she had a 2 point lead on him in the finals, and she lost.
That's how it went down as a shocking victory because at the time we didn't realize the magnitude of the charming male vote, the vote for Julianne winning the previous season.
Had that result of Helio beating Mel happened 10 seasons later and we would have predicted it, and not been as surprised by it.
By with Bobby he was someone we all assumed would go far from his fanbase. I saw various predictions thinking he'd go out anywhere from 7th-4th place, but in most seasons when the odd man out made the finals (Bill Engvall, Drew Scott, David Ross, Bristol to name a few) they always got some form of 4th-2nd place.
The shock of this comes down to that that "odd man out" finalist actually won. I blame many reasons. I blame the movement to get Sharna a win, I blame the fact that his fellow finalists didn't have that single strong backing like he did. The shippers got Alexis far, but the majority got tired of the showmance. Evanna and Milo had a strong backing of Disney and Potter fans, but a lot of casuals split their vote between those two. Add in the weird one night finale and weird last week votes mattering for the following week that we had, and it created the storm that was Bobby winning.
I don't care how many more seasons there are, 28, 31, 35, he will probably always be regarded as the shows least talented winner.