Why are rewards for the new savage tier locked behind 'order of story-progression'?

I dont have a group to raid with so I hop in PF for all my raiding needs (yes, I am absolutely a masochist). I found out yesterday that you FORFIT WEEKLY REWARDS if you don't do them in order. I did not clear Umbra Savage yet, but got invited to practice Litany, but upon getting the 'Join Duty' prompt thingy, I was given this weird message saying that going in without clearing Umbra first, would make me forfit the rewards from Umbra. And sure enough, after practicing Litany, I look up Umbra Savage in Duty Finder and it says I got the rewards for this week without actually having done so.:confused::mad::confused:

What is the logic behind this? Why can't you do it 'out of order'?

The fights go progressively harder in order. Therefore you must complete them in order. This has been the design philosophy since they added raiding in ARR.

You have to wait until they "unlock" savage for you to do it in any order you want. That won't happen for this tier until around 5.56/5.58 or so.

Not just 14, many games with Raids do the same philosophy.