A tool is whatever you need it to be. My dad used to hammer in nails with a pestle for years until we got multiple hammers and insisted he use it.

While traditionally announcements were made over the blog, it's a bit of a clunky tool at the current point, and to a big extent is more aimed at an external audience than the core user base.

On the other hand there's this old, almost forgotten diagram 

[![enter image description here][1]][1]

which once resided in the about page - and that really does reflect meta well - least for many of us, it acts as a community built repository of knowledge (aka a wiki). It's a place for announcements, and acts almost as a secondary blog. While I'd bristle at calling it a forum in the modern sense - it is a place for discussion. Not sure about these digg/refit things. 

In a sense, folks at SE found that the 20 lb sledgehammer worked less well for their needs here than one of these

[![enter image description here][2]][2]<br>
<sub>[By Agolz12 - Own work, CC BY-SA 4.0][3]</sub>

It's a multi purpose tool that does many things. It might not be the best tool for driving in stakes but... that's not what we always need. 

So meta *is used* by Stack Overflow in this way since it's the most efficient way to get information through to the broader Stack Exchange Userbase.

  [1]: https://i.sstatic.net/FHX9P.png
  [2]: https://i.sstatic.net/bj9QA.jpg
  [3]: https://commons.wikimedia.org/w/index.php?curid=38908865