I had experience on all type of website (since I was trying to build a small PBN ) even I agree with about site contents , but this is not all matter for G , even on my niche I saw many pages ranked 1st for less then 200 words , while some my main site articles passed 1000 words , and they didn't rank ,
simply because there is other sites have higher Authority then me ranking on tiny contents , I'm 100% sure that my site have better contents better in page SEO better user experience and even faster load speed , but G completely ignore it .
The problem with all my site is the niche are very popular and everyone try to compete on it , if I wire any article on targeted KW I'll have at least ~ 300 blog sites web-forums who write about exact same KW ,
Think about it like tourism site , and write about Hawaii vacation tips if my site didn't have any sort of authority G won't give sht about my contents at all no matter how good it's , my nice niche is not that competitive of course but it have too many people write on it , if I got authority to my site equal to PR5 I'll rank first on every major KW on that niche , 5-10K visitor / day will be easy