I think it's mainly bc there's no evidence suggesting that even if the team was fully healthy that'd we'd be serious contenders. Our major weaknesses are run defense, oline, and receivers. Lines had next to no injuries and were still subpar, while we're one concussion away from Shaheed being our WR1. I think we've seen the team healthy in 2023 and there's really no evidence that we'd be much better than that going into 2025. Maybe an 11 win ceiling if literally everything goes our way. Then our team would have to start playing actual teams in the playoffs, which seems grim since we've beat next to no .500 teams in the past couple years.
Additionally, it's worth saying that injuries will be a fundamental problem even heading into the season. With how old so many of our stars are, the risk of injury is going to be very high and thus we need to factor that in when realistically accessing the team.
For some of the truthers, I really would encourage as a thought exercise to rank the Saints when compared to other teams. Saints can seem like they're pretty good when viewed in isolation, but soooo many teams look so much better when in comparison. It all just seems really grim.