Wasn't till this playthrough that I realized the dark brotherhood and seems like a few other quest chains actually remove/change things so certain misc or side quests are no longer available (Narfi was the one that brought it home, was going to tell him his sis was coming home soon... but nope just had to kill the poor guy without giving him one last glimmer of happiness first)

But looks like a couple quests break others, not just bugs but deliberate changes (not counting season unending...)

Brings back memories of morrowind when your choices mattered a lot in doing quest chains (point of no return and all that)

Which is why I went back to previous save game... first order - all the side quests! Then the quest chains!

For the loot! And ocd...