Facebook political ads

As more and more people are getting their news from Facebook, does Facebook have an obligation to censor false information or is it simply a forum for open discourse?

Recently Mark Zuckerberg has come under scrutiny for his decision to not fact check political ads.  He has even been hauled into congress and grilled by lawmakers, but still no widesweeping changes:

https://edition.cnn.com/2019/11/07/tech/facebook-political-ads/index.html

There are laws that prohibit companies from making false claims in advertising, but none for politicians and other news sources are more scrupulous when it comes to what they print or broadcast:

https://www.houstonchronicle.com/business/columnists/tomlinson/article/Facebook-could-learn-better-manners-from-14830080.php?utm_source=desktop&utm_medium=collection&utm_campaign=hcpromomod

Should Facebook fact check or sensor material or should it allow people to say what they want and have the onus on the public to research and decide for themselves?  This is a big point of contention right now and I'd like to get your opinions on the matter.