I did not know, however, that Seals could not drop in Tide. Thank you for that information, unwelcome though it was (not your fault though...game mechanics are what they are, right?).
But you're making an even better point here, and that is these quests have very few chests in them so, even assuming that any chest can drop a Seal, when you're talking about 1 or, rarely, 2 chests in a quest, you're going to have to complete many runs of the quests to see one drop as opposed to a quest in which there are, say, 5 or 6 chests.
Yeah, the scroll drops are the saving grace here. If I was going 20 quests without seeing one of those drop, I think
I'd give up and start playing Hello Kitty Online.