Exactly Doc. I've got global cat running on a local dev install, including using full urls (site.tld/tags/the_tag/).
Also, you can create a community with it. It is what you make of it, and that's that. It took me all of about an hour to implement a "friends" list, and also allow logged in users (that have the plugin enabled on their account) to see a link to add someone to their list when visiting a blog that has it enabled (and opts to display the link).
I can display the most recent (X) number of posts from the network, and I also have added an option where all posts are not only posted in their respective blog, but also archived in a single blog.
It is what you make of it. It's like stuffing Ford for making the Mustang simply because someone thinks it should be just like a Lamborghini, or slogging the Linux community because they don't understand how to use the system. It's ridiculous. So, faulting MU for someone's own shortcomings isn't right either.