The only reason Warframe works as an offering is because DE is making so much money from content creators and esentially donations that they can afford to make every single gameplay thing in WF completely free and almost every single cosmetic thing too. The protoframes were DE's biggest cosmetic investment and they were still free.
Doing that same content loop by a studio that does not want to do that results in a game that has zero reasons to be played. Why would I play a grindy game when I also have to pay to unlock the ability to even grind for those things?