How Symbolic

A symbol is a sign that represents something else.
A star, in a theatrical context, is someone that plays someone else or possibly something else.

Based on those definitions, you can say that stars are symbols.

Look at the phrase "Sex Symbol", which in most cases we are talking about stars. It has a nice ring to it. Most sex symbols are musicians athletes, models, or actors AKA Stars. Since symbols can be stars lets take the phrase "Sex Symbol" and replace the word symbol with star. Now we have a "Sex Star", it doesn't sound like something people want to be, unless you are into porn.