So you are telling me that through all his journey in Teyvat.
The traveler never thought of training his elemental powers and use them all together?

honestly who cares what they think
I feel bad for Kazuya, hes mentally ill and clearly doesnt notice. Hes not in his right mind and Chizuru is an evil scum like person who clearly deserves to rot in hell for taking advantage of someone who is clearly not capable of making decisions on his own.