During his time as Leafs GM, Kyle Dubas had traded 7 first round picks, which break down as follows:
2018: traded down from 25th to 29th (Rasmus Sandin) & 76th overall (Semyon Der-Arguchintsev
2019: traded in Jake Muzzin deal
2020: traded to Carolina to dump Patrick Marleau's contract
2021: Traded to Columbus in Nick Foligno deal
2022: traded down 25th to 38th (Fraser Minten) to dump Petr Mrazek's contract
2023: traded to St. Louis in Ryan O'Reilly deal
2025: traded to Chicago in Jake McCabe deal
Dubas is not a clairvoyant. There's no way that he could have anticipated Jake Muzzin's string of concussions, Nick Foligno's crippling back injury shortly after his arrival in Toronto, Petr Mrazek's play plummeting the way it did and the lack of playoff success last season with all of the impact moves he made to address multiple roster needs, bringing in O'Reilly and McCabe, among others.
Still, even though it wasn't his intent, it doesn't change the fact that Dubas has set the Leafs back a long way with how he chose to use his 1st round picks. Not only has the impact of these decisions been felt in recent years, but it will also be felt in the future.
In the end, the Buds hired ex-Flames GM Brad Treliving to replace him, and while we don't yet know whether or not he'll be an improvement, he can't possibly be any worse from one specific perspective.