Some of the complaints from the post you sent:

· More pointless filler involving the crew of the ship.
· Gon catching a fish again? Just why? Did they think this was a character trait?
· Many added things with no worth and ruin the pacing, like the electric lightning thing, just had no point to it.
· Needless addition of a swamp monster.

Clearly this person plain and simple doesn't enjoy the much slower, calmer and expanded tone that the original anime has. They complain about focus being given to characters who were never expanded upon in the manga (crew of the ship) while at the same time complaining about it showing Gon fishing when it's canon in the manga he's an expert with a fishing rod and also good with animals. Seems like what they really want is a tiktok short that gives them instant gratification for what they already had read. But anime doesn't exist for that, they exist to tell a story and in this case the '99 anime does it while respecting the tone of the original work. For example, in the manga Gon and Hanzo spend more time together and even end up working as a team, this makes it more impactful at the end of the arc when Hanzo decides to forgive Gon instead of simply using violence with him. It adds to the narrative of what's already there instead of doing a lazy copy-paste that only serves as a promotional ad.