But the point of Diadem is not farm ilvl 210 items, point of that duty is complete objectives. Which i mentioned before, collect 8 bronze chest, botany nodes etc.

Farming ilvl 210 on dino island is same like you skip that chest in Brayflox HM after 1 boss. Its optional. Social expectation are all subjective.
Maybe somebody also want that chest in BFHM but we skipped it, maybe somebody also want optional rooms in Haukke Manor. Its all subjective and not part of duty objective. So you may ask people to help you there, but you should not force them to do it.

However I agree that design of Diadem is bad, good idea - bad design, again SE. But i dont blame players for that. I wrote my expectation of Diadem in other topic here how my design should looks like.