If you have a group of trusted people who you know and trust and would like to setup blogs for them then you can do that with mojoPortal very easily.
However mojoPortal is not designed to be a social networking platform, it is designed for business web sites with social engagement/interaction. You should read carefully What mojoPortal Is NOT Designed for on our about mojoPortal page.
You should not let strangers or just anyone who registers on your site have a blog, the blog is too powerful and is only designed for trusted users. It allows use of javascript because there are lots of good things one can do with javascript but if you let a bad person use it he can put in malicious javascript to do bad things.
It is possible to build features with less power that would be safer for use by untrusted users, but you would need to build those features yourself, it is not a goal for the project.
Hope that helps,
Joe