Not sure where you're getting your information from: Google platformed hardcore porn up until 2015 [0]. Tumblr permitted it through 2018 [1], while Reddit and Twitter allow it today.

[0] https://news.ycombinator.com/item?id=9098875 ("Google bans 'explicit' adult content from Blogger blogs", 2015)

- "Until today, Google's Blogger platform previously allowed "images or videos that contain nudity or sexual activity," and stated that "Censoring this content is contrary to a service that bases itself on freedom of expression."

[1] https://news.ycombinator.com/item?id=18590944 ("Tumblr will ban all adult content on December 17th", 2018; 464 comments)

They usually have them in order to not spook the advertisers who don't want to see their ad near anything remotely objectionable. Don't see why they care about somebody sharing a document from their Drive.