The key difference is that the eventual winners could choose to run the time down so that they can all build special and have an unbeatable quad special combination that takes the mid point, thus securing penalty time (to the tune of three quarters of whatever score the opponents just got) that allows them to have a second attempt if the other team has a "fluke" of their own and retakes the point, but in Turf, you're forced to make a move at the 25-30 second mark in order to have enough time to push out and take over the map or choke the map out and make such a comeback impossible (depending on which side of the spawn camp you're on).
Furthermore, consider that defending on some maps is so much easier than pushing (see Arowana, Saltspray, Mackerel once you get set up) that being able to secure a point for an extended period of time is not necessarily indicative of superiority, only a "fluke" on the first engagement (maybe they have a 96 user, for example, whose gun decided to shoot straight for fifteen seconds). If the losing team is the superior team, they will get about four good pushes in before the game ends. That's four opportunities for them to outplay the other team; maybe they luck out and it takes one, or maybe it takes all four and it gets down to single-digit points for the other team, but they then get the same advantages that the inferior team had, and can almost certainly win the game.
In this sense, "flukes" have a chance to balance out. There are five whole minutes for one team to emerge victorious, and if neither of them do, then they're evidently matched closely enough that a deciding factor needs to break the tie. A single "fluke" at the end of a Turf match wins. No counterplay, no preparation, nothing to do except hope to hell the other team all decides to ink their feet while they have complete map control.