If you're talking about the daily quests in the quest hubs, it's because they take place inside instances (i.e. Skyreach Catacombs). Your quest progress shouldn't reset, but the enemies within the instance might.
This happens in many many quests as well. Murkmire was the best example i can think of . I had to redo one quest four times cuz i got booted from server.
Why do Craglorn quests reset to the start once I need to logout and login again?
Is there a way to avoid this? It's just frustrating that all progress gets invalidated.
A lot of quests have this. It's because questprogress is only saved at certain point, most of the time not at all. Even doing a dungeon halfway a quest will usually reset it.
Huyen Shadowpaw, dedicated nightblade tank - PS4 (Retired)
Huyen Swiftpaw, nightblade dps - PC EU (Retired)
Huyen Lightpaw, templar healer - PC EU (Retired)
Huyen Swiftpaw, necromancer dps - PC EU (Retired)
Huyen Swiftpaw, dragonknight (no defined role yet)
"Failure is only the opportunity to begin again. Only this time, more wisely" - Uncle Iroh