If you don't want to create an account, you can still post a review on a business. But keep in mind you will not be able to modify your review afterwards if you post as a guest.
We encourage users to post as registered users instead of guest as even as a registered user, we will never show your full name. Also if a business owner/manager disputes an anonymous our moderators tend to favor the owner. Member reviews have a higher level of trust and given priority.