The links to Stack Overflow's 'Twitter' and 'Blog' accounts are missing under the Stack Exchange 'All Sites' listing. If you look at the 'Super User' or 'Server Fault' (and few others), they do link to 'Twitter' and/or 'Blog', if available. For example:
I am aware of the fact that Stack Overflow blog i.e. blog.stackoverflow.com is the same as (or combined with the SE blog) blog.stackexchange.com but not sure if that's the reason for not displaying the SO 'Blog' link.
Also, Stack Overflow does have it's own dedicated Twitter a/c: https://twitter.com/stackoverflow. I am curious to know why SO's 'Twitter' link is not displayed as well.
As per the Normal Human's comment:
Stack Overflow does have a Twitter account now, so the question of why it isn't linked makes perfect sense. The list does not say that the account has to be a bot...
Can anyone please explain or point me to any documented evidence on the same.