A few things have happened that make this a good idea.

1. Steemit.com is connecting to facebook during every page load. See that round user headshot icon? At one point they coded something that showed everyones Facebook Headshot there that registered with a facebook account. Massive breach of user privacy!
2. Steemit.com was hacked and lost many accounts and a bunch of steem. This security breach was purely due to releasing software without security testing, and it cost people time and money. No serious security features have been implemented since, just a removal of features and password change feature for after the fact. That hacker could have easily gotten the facebook\reddit accounts used to register to steemit, we will never know.
3. Due to the hack, the "accidental" facebook connections, the lack of precautions after the hack, and the general avoidance of normal customer service features like a helpdesk, I just assume that there is very little thought put into user info security.

That is why this is a great service. Thanks for providing it someguy123!