Viz's translation of One Piece isn't 'unforgivable' that is absurd hyperbole.
Its just seems to be a bit of a mess. Especially the more you look into it.
Even if you ignore the big reoccurring mistakes like 'Zolo' and 'Teech', there seem to be a ton of others that are just bizarre like calling Chopper's moves 'boosts' instead of 'points'.
Where they got the word 'boost' from I don't know. Its literally written ポイント(pointo)
While I can forgive random scanlators on the internet for making mistakes, I feel Viz should be held to a higher standard with their translation, they are selling it after all.
But its not exactly the end of the world. Just a bit disappointing.
The problem is that those translations all came from a time when 4kids was the main inspiration for translations, and most of their staff couldn't translate garbage.
Even their old translators didn't have a strong grasp on the characters at all. I think in one interview even, one of the older translators said that Luffy is a hero, so that's why he would never curse. That sentence alone gives you an idea of the quality of translation previously.
For the most part the great translations didn't come until late Fishman Island, when Stephen took over. Just listen to the One Piece Podcast and you will see just how in tune he is with One Piece (it helps that he once did scanlations once upon a time, so he comes from our ilk).
The problem is, that there are over 60 volumes of spotty translations before then, so that's what most people will see.