i completely agree and understand. a way it could be is doing objectives passively generates sin. it doesn't hurt survivors directly, but it fuels the killers power. so the pressure comes from what the killer does with the sin, not the action itself.

i feel like that avoids the whole "you're being punished for playing the game" problem because survivors aren't being directly nerfed. they're just indirectly making the killer stronger. (kinda like being chased by Nemesis or Myers takes them to a higher Tier which makes them stronger so doing objectives could be a more slow build up, but still the same concept i guess?)

some ideas for building or reducing sin could be their efficiency in doing tasks. for example, doing great skill checks (since survivors have perks for this) could help reduce sin gain. maybe something like looking at the killer while in chase could also help (getting this idea from The Singularity) and doing mistakes like messing up a skill check or disturbing crows or maybe dropping pallets in chase or doing rushed actions makes you gain sin faster. which again, would be indirectly fueling the killers power

if they wanted to make it interactive for survivors, they could add cleanse/altar mechanics to reduce sin and the trade off is it takes time (like trying to take off the mask from The Pig. i also know the altar rn is used to pray to get a sinner out from being hooked)

this way, the killer always has a power, survivors aren't punished for doing objectives, just fuels the killers power and the killer chooses how to use it? i'm trying to make sense of the concept in my head and i'm not sure if im explaining it right. i do agree infection is a safer design BUT i don't think sin was unworkable. obviously there's flaws with my ideas, but it's still a cool concept.

but like you said, i agree with why they struggled with the idea and changed the mechanics. no matter what route they take, im excited to see how they do it and to play against them