True, but you don't get the mileage you'd want compared to if you main an element with active events...
You run at worst 50 raids to get your 100 regalia fragments. Host and that's 50 cleared (as far as I'm aware you get 1 regalia per spawn?), and you gain the 20 from shop. Which equates to another 50 left. Plug in the numbers (subsequent raids yield 1.2 regalias each) and you're basically left with only 9 regalias required to be traded. Of course, variables here don't include raid assist, but it does say something about not hitting the 15 per regalia mark if you host your own raids.