So I've tried to think of things I've been asked more than once. And one is the title there: everybody and his brother Simon, King of the Witches, has a website or blog or whatnot that they own. Their own domain, their own corner of the Web. Do you need one too?
The answer is honestly probably not. But the main question you need to ask yourself is: what are you trying to accomplish?
Most people just want a place so that they too can be heard. Read. Whatever. If you just feel like blogging about your cat, then perhaps you don't really need your own site. You might be fine with using your Facebook account, or even that old standby LiveJournal or just going and getting a mycatrocksyourface.whatever.com at some place like WordPress.com.
Seriously. They're free, there's no infrastructure for you to support, and your cat's three fans can read up on its latest adventures and whatever you dressed it in this week.