Recently, there's been a big stir in the writing world, especially among small-press and self-published authors. It's taken different forms, but the main point boils down to whether or not authors can share links related to their books on their personal Facebook profiles.
The issue is multi-faceted and only affects Facebook. That's because FB separates business pages from personal profiles and doesn't allow either seamless integration or multiple personal profiles. Platforms like Google+, Twitter, Instagram, Pinterest, etc. allow you to use the same profile for everything or create multiple separate accounts. (I believe G+ requires separate Gmail accounts to link, however.)
If you're on Facebook and haven't seen it, here is one author's post. It's a bit overly dramatic, and not everything in here is strictly true. When I dug around a bit, I found that this policy has been in effect essentially since FB introduced Pages. They may be cracking down on it more lately, which probably has more to do with wanting to earn money from business page ads. It's also not likely meant to target the average small-press or indie author, nor will it hurt them if they're not consistently part of the problem.
Part of the issue is that it's easier to add friends than to convince people to like a business page. It's certainly tempting to set up a profile under an author pseudonym or even use your own legal-name profile. But then it gets into tricky territory. Is that befriending people under false pretense? How many book-related posts are too many? Where is the line between friendship and readership?
This is one time when Facebook may be right. Profiles used primarily for selling things to other people are, at best, unpleasant. Most people don't send or accept friend requests unless they're interested in social interaction. If they're then inundated with countless ads and promotions, it becomes tiresome and a mess to wade through for funny memes and updates about Aunt Jane's surgery and cute baby pictures.
The occasional work-related post probably isn't a big deal, especially for people who share all kinds of other non-work posts. Talking about aspects of the writing process or sharing (without links) bits of works-in-progress also seem fine. It's possibly a little tricker to share things that have a distinct promotional flavor, but those are mainly at a person's discretion, as long as it's not constant. Some authors have said they couldn't share book launch events. If that's the case, it's probably okay to mention there is one and tell people to message you separately for the link (or link to a business page that has the info).
Supposed Crimes obviously has this blog on our website, which we share to our business page. Many of our authors have their own Facebook business pages. Our readers can follow them there for updates. Beyond that, if anyone still has concerns or questions, this article is a great summary with suggestions for how to avoid being blocked for content.
Reality is, many readers don't find us that way anyhow. Word of mouth (rather than authors bombarding their friends lists) is ideal. So if you like stuff you've read or you have a favorite author, share them! Readers can't get in trouble for sharing about new books they've loved, and if you're keeping up with an author page, you can share from there. Even better, make sure you're rating and reviewing books you enjoy so other readers can find them.
As for the ban on too many promotions, think of it like the Highway Beautification Project (limiting the number of billboards allowed) or avoiding those annoying websites that have constant pop-ups. Keeping Facebook profiles for social interactions makes sense for those of us who prefer not to have our conversations interrupted with more bold-print ads for stuff, no matter how much we love the person selling it.