The mission of blogging is to empower all of us to go directly to each other with our expertise. So if you know something as well as anyone else, or you learn something or know something that should be shared, then you should share it on your blog
That's true, and yes short messages like tweets often vanish into thin air, blog posts don't. They have a better lasting value, but using a new kind of social network like Google+ is another thing. Google+ is a modern way of blogging. Yes we don't have archives or formatting tools there, but we have an excellent search engine. I still have posts from 2011 that pops up and get interactions. That's what I call a good lasting value.