Unlike Google, Facebook's contribution to human knowledge and useful dialog seems to me negligible.
First, you can like someone's post, ignore it, but never dislike it. This has the effect of distorting reality, and strongly discouraging those dissenting individuals from participating.
We can reference a blog entry and its comments, or a web page trivially using their URLs. In contrast, it is not obvious how to reference a Facebook comment. We can conclude that Facebook comments have little reference values. For example, researchers using Zotero to collect references will find few if any Facebook comments in their collections.
I found a Facebook public event named 連署要求NCC對《三立》假新聞開罰，勿再縱容惡質媒體!!
I left a comment, encouraging event supporters to provide evidences to garner more support. My comment was removed within minutes.
An event participant 董倫輝 wrote
馬總統完全在狀況外，被惡質的三立擺了一道。It would be useful for the society to ask why he knows, given Ma Ying-Jeou's notoriety. See 我們家沒有人有綠卡; 我有綠卡, 女兒是美國公民.
Another, 杨垂沿 wrote
中國國民黨/共產黨 如何摧毀人性 How KMT/CCP destroy human decency presents facts after facts of such evil-doings and worse.
At this writing, there are 466 event participants in this Facebook public event named 連署要求NCC對《三立》假新聞開罰，勿再縱容惡質媒體!!. I asked these people to explain why Dr. Jerome Keating was wrong by having a different opinion at Taiwan, the Ma Government Wants the Media to Serve it. My question was deleted within minutes.
Overall, Facebook is transient and provides little of lasting values.