Re: BP advertises “WordPress Blogging” .. but how?
You’ve sort of taken two slightly different responses and tried to meld them into one, you originally asked about users being allowed to contribute/provide content ; I pointed out that you can allow selected users to write content on the main blog that BP runs on, it was also mentioned that MS blogs could be enabled, if you have enabled MS you now have two options to allowing users to contribute content on the site.
You do not create user blogs yourself the user creates the blog themselves and in doing so is automatically the admin for that blog, bear in mind that these blogs are full standalone WP blogs, I doubt you want to be creating them manually on behalf of your users, you could do though.
The other option is as I mentioned originally and to which you allude to in asking “and grant them the author level manually?” you would be doing this if you wanted to add authors to the main blog.
You might need to clarify for yourself the distinction between user blogs and what is often referred to as the ‘Main Blog’
