This is true. But what it comes down to is, do you bias a system for read performance or data size? We have biased the system for read performance ( feel free to read up on fan out on write vs. fan out on read ). Also, the notifications system creates node async to the blog creation process so that ...

You can use the "Review Summary" component which will show you exactly what you are asking for, each rating averaged of all users who have answered. You configure it by editing the component using the author and point the "Review Path" to where the reviews component you want a summary for.

Can you see if there are any Javascript errors in the browser console? Often if there are no errors in the server log it might be a simple issue of not having the JS included on the page ( especially if you are testing this from a Publisher node).