Why seo provider like to offer crap spun article?

I have seen on several forum, wf, wicked fire and even bhw, the seo provider like to offer 1 original article for tier 1 and spin it on high level, resulting a crap spun article with huge grammar mistake, with same number of paragraph and sentence (too large footprint). Doesnt it bad for tier 1 backlink? I think google has algorithm to detect spun article, something called n-gram if im not mistaken. Do you guys (customer) really use their article or likely to provide your own article?

First, It will cost too much time and money for the provider if they will provide unique articles on every backlinks.

I tried to make a 400 word article with wordspin, sentence spin, and paragraph spin. And It took me 10 hours to complete it. Damn!

Another problem is the topic, if they will write unique article for every links. They need to research on the topic before writing an article.

Yea, but i think manual multi-level spun article is better, but still it cost some money, how about scrape article, combine it and using a better thesaurus to spin the article? I think its better than 1 original ultra spun article.