Smarter people tell me that what you're asking for is rather tricky to do.
Kinda reminds me of people asking the same for MultiUpload years ago when that extension was maintained & usable, and I guess the "best" solution is still the same as it was w/ MultiUpload: let's just assume that people read the fu--fine manual, and/or source code and will amend their local MediaWiki:Sidebar or equivalent page as they want to. When you have the right to access Special:CreateBlogPost, it'll show up under Other special pages on Special:SpecialPages, so it's not totally hidden at least. (Do you have a better category in mind? Suggestions/patches welcome! 👍 )

For social profiles, the Challenge extension uses the UserProfileGetProfileHeaderLinks hook to add a "Challenge this user" link to user profile pages. Maybe you can use that hook to implement a "Create a new blog post" link or so. (Personally I am inclined to suggest against this on a general level because the profile links section on your profile is currently decently "busy": Edit profile | Upload avatar | My watchlist | Contributions | Wiki userpage, though of course this depends on the chosen UI language and skin. At the end of the day, you know what works best for your community, and I'll gladly take a look at relevant patches and voice my thoughts on them.)