If it comes preinstalled, you have a complete blog with comments, etc. by default, ready to use, and a ton of themes. Anything else, you will need extensions. There are a lot, but if something doesn't fit, though luck.
Other CMSs (like Drupal) are much more versatile, so you don't need extensions most of the time. But they are much more complex to configure and administer.
If it is for OSNews, I reckon it will suit you perfectly.
The most idiot proof way to host it is in Wordpress.com, because in the cheapest tiers they don't let you shoot your own foot installing themes or extensions, and they manage all the updates and security fixes; in fact, creating and managing a blog in the free tier feels a bit like creating and managing a Gmail account. You can use it to wet your feet or try it; and then migrate to a dedicated hosting if you need/want it.
Well, then you are already down the rabbit hole. You are doing already 99% of the stuff (posting+updating+making backups). The other 1% may be solved by hosting support or Google+community. If you are lucky, that 1% may not even exist (I'm talking about rare cases of botched updates, daemons not running...).