I specifically created an account to reply to this.
I absolutely love it, when I put together a question, provide arguments and counter arguments, and all of this is ignored in an answer, addressing only a single line of my 4 paragraph email.
Is there a hardcap? Probably. At least in the tutorial it says the max number is 7, afterwards it doesn't specifically state this again for each scenario. However it is implied again and again by the game that, if you have to take a card that isn't there, nothing happens. There are 7 cards in the game, so probably hardcap.
Yes, you cannot "double-dip" on Hope Reborn cards. Especially if you have buildings that give you hope reborn cards or as the OP stated side quests you end up every scenario with way more HR cards to draw than there are.
Does that mean that engaging with content is, for the most part, unrewarding and potentially dangerous in 7th Citadel? Yes.
As a campaign with a certain setting and difficulty there are only two type of rewards that can be given to players to help them overcome higher difficulties: items/knowledge/utility actions and experience, to be cashed in to make certain things easier (i.e. a certain number of prestige to get into Kel without paying, etc.)
To keep a campaign interesting or challenging and not a roflstomp toward the end is difficult for game design.
We are currently at the mid point of our first threat book and have finished every single scenario so far with ~ 10 HR card where it not for the fact that they are limited. We have about 8 sidequests, and have finished one so far, with little to no progress on the others.
Maybe we were exceedingly lucky, but we are also permanently at weight limit for items.
From here on out there is very little reason to do anything but rush the scenario goal and not engage with anything else.
Rushing is also somewhat recommended by the scenarios, as they usually have some kind of end-boss or tough consequences. Then you sit at 7 HR, 5 glimmers and 15 HP per player and there is no reason to do anything but close out the scenario.
On the other hand the destiny meta progression is, also for the most part, minor impact, with a few OP things to aim for.
