Why Doesn't Facebook Allow Polling?

This Status by Senator Ted Cruz (~600k page likes) currently has over 56,000 comments.

Facebook is the perfect platform for polls. Users want to engage with current events but there is no medium, such as a poll, to easily compile opinions. Why is this? Polls not only foster engagement, but also provide quality real-time content that users find interesting (and can lead to reading time if implemented correctly).

My idea for polls:

Using the picture above as an example, Senator Ted Cruz offers a poll for the question: "Are you better off with Obamacare?" with options of:

- Yes
- No

• Obviously, once someone votes, the percentage and number of votes for each option will show. 
• Comments should be separated into two categories: those who are better off with Obamacare, and those who aren't better off with Obamacare. This way, viewers can see both sides of an argument. Of course, "Yes"users can respond to "no" comments and vice versa for discussion/argument purposes.
• Anyone who votes will have their answer included so it is easily known what side they are on. In the above picture for example, all users will have their opinion answer in the right corner of their individual chat box.

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There are a lot of benefits that I won't get into because I think they are pretty obvious. Maybe most importantly, polls offer another form of engagement; one where an individual doesn't feel inclined to "share" something (read: an endorsement) or "like" something (read: doesn't provide context).