Because fishing is difficult asf and we don't have any stuff like in stardew to make it easier (well technically there is but not as varied you get the point)

You have to wait, and wait, and wait, and wait

And then you have to wait like an idiot again

Until the fish finally bites and then you don't get it because it's a mek from fontaine which are extremely difficult to catch

^^^This proves Tartaglia is actually the strongest harbinger since he is canonically an expert fisher

Oh let's not forget that fishing requires a lack of skill issue

^^ You think he ever gets bored of waiting and just uses his Delusion on the water to pre-fry 'em?

^^^ Let's not forget our boy Freminet ... sure he can catch a lot of fish ... by hand.

Arlecchino grabbed one straight out of the water as a child

The reason I like silver spoons.

Cast and reel in, and repeat. You actively fish.

There is also fishing with a net, fly fishing, noodling, spear fishing, and so on.

Traveler is not powerful lore-wise. The only boss we have managed to defeat without any help is Signora, so we can say that the Traveler's power level is simply above the 8th Harbinger level. Childe ran away from our fight after he realized that there was no Gnosis in the Gold House, we didn't even manage to land a scratch on Arlecchino, we have defeated Dvalin with some kind of blessing from Barbatos, we didn't ever defeat Raiden - she only stopped attacking us when Yae intervened, and Scaramouche beat us 168 times (if i remember correctly) before Nahida granted us the wisdom of all of Sumeru , which is the nation with the biggest number of educated people + her little silly pet.

*exhale*

And my personal, canon opinion about genshin's fishing is that I just suck at it (proud no Catch haver)

Against Raiden, traveller was powered by all the stolen visions, and the same way borrowed all of Sumeru's wisdom to take down Neon Genesis Scaramouchegelion

Fishes, however, are superior lifeforms out of all bounds of reality. they don't care for power nor status, all Gods will fall against them

The rays hold the secrets of the universe

Fishing is just hard ig idk lol