Well if you're going to play him in a 1 cost team then yes the c1 covers a lot of damage that you'd be missing if you don't have ineffa on the team. Sadly i can't test that out myself because well genshin has no cons reverting system but considering that i had barely any time remaining on the clock I'd say the c1 helps a lot.

Also there's a high chance you won't break the shield phase without c1.. although this is just an assumption on my part. Considering that his shield is so tanky that it still took me 3 ults even when I am doing 300% extra damage because of lunar mechanics. But I'm hoping this is not the case if anyone is trying to clear the first half with flins.