When we're new, or returning and need to farm gear, or simply a solo player, there are many leads and unique furnishings that drop from tasks that are really hard to solo. For instance, there are leads that drop from the Galen and Deadlands Walking World Bosses. A unique furnishing drops from a WB in Blackreach (the harmonium). And if we're not playing when those tasks are first released (and mobbed), it can be really hard to get those leads/furnishings. Sometimes an event that revisits a zone will help, but those are too rare for this purpose.

The big thing, though, is the drop method would absolutely have to change or it will be nearly pointless.
If I'm a lvl 30 character, I'm never going to be in the top DPS and thus get the drop from a walking world boss during an event. So there would have to be a chest or otherwise a way to guarantee everyone who gets a hit in would have their chance to loot the lead/furnishing plan. Maybe this would be a step towards changing that drop mechanic all throughout the game.

Not every challenge during a season. Just one or two per season.