Why are more of my friends on Tumblr via Twitter vs. FB?
Lara Druyan stashed this in Tumblr!
Stashed in: Fixitfixitfixit!
Is there a reason for this? I have 13 Twitter friends on Tumblr but only 1 FB friend (of the same group)....
Anecdotally, a lot more people I know seem to have their Tumblr's authenticated with Twitter (for tweeting) than Facebook (for sharing on Timeline).
Twitter and Tumblr feel very compatible -- they're both public microblogging services.
Facebook and Tumblr feel not as compatible -- Facebook is private and who you are, whereas Tumblr promotes public posting using pseudonyms.
I especially don't want to connect my NSFW Tumblr to My-Mom-Reads-This Facebook. So not giving Tumblr my Facebook credentials is an easy way to ensure that.
I just tried the Tumblr lookup app, too: http://www.tumblr.com/lookup/
It found 50 blogs based on my Facebook.
It found 1000+ blogs based on my Twitter.
So, consistent with your findings.
Could be a limitation in the Facebook API, or it could be a Tumblr bug.