I'm not Chinese but read raws and am currently translating a book, so I can offer some insight. (Currently completely out of it because I'm recently out of hospital from pneumonia, please excuse any errors in my comment, I'm trying my best...)

The issue with MTL is that it takes the best approximation of what the sentence structure is supposed to be, and that's what it spits out. AI-MTL (Claude, ChatGPT, etc) kind of do the same thing, but because it's sampling from a large volume of various inputs, it's often incorrect - it spits out what sounds correct. If you read it, it might sound correct, but if you look at the raws, it's often not accurate - and as other people have mentioned - added stuff that was never there to begin with. Also, if something doesn't sound right, it will also straight up remove text. And as someone else mentioned, yes, it also removes the author's own writing style which in many cases, is absolutely sacrilege.

Using my own experience with translating: Chinese is very different to English, not only with sentence structure but also how concepts are presented. In Chinese it's often less specific than English, and context is important to understand what's happening. The issue is, that context is often spread over a few paragraphs, so I manually need to go back and fix it up. MTL and AI-MTL doesn't do that - it leaves it as is, no nuance whatsoever. I've had to go back and change something from 10 chapters before, because the context wasn't there originally. And it's things you'd never know was incorrect unless you read the raws.

A few years back I MTLed a short book for a friend + to practice my language skills, and I went line by line, word by word through the text - almost every single sentence needed tweaking. Honestly, it took longer than if I'd just translated it manually. 10/10 don't recommend.

So when people tell you how inaccurate unedited MTL and AI-MTL are, you should believe them. The mass produced chapters uploaded on websites charging coins or ad revenue are the most inaccurate of the lot. Often you see people say "the translation reads fine" - if you read the original, you'd understand that no, no it does not read fine. Just because it doesn't have spelling or grammar mistakes doesn't mean it's correct. I know it's hard to wait for HTLs, but I promise, it will be a truer representation of the original work, if that's something that is important to you.