You don't state the reason to do that, so the general answer is no.
About the specific question, no, it won't hurt your SEO in any way because is basically a rule that nobody would pay attention to it.
Potentially may affect you badly if you make a mistake and block a folder that has content, but assuming you won't make that mistake, there is no benefit or drawback.
After Panda 4 update (May 2014), blocking css & js files will kill your seo.
There is a nice case study here that shows how doing that can hurt SEO :
Nowadays Google wants to see your pages as same as users, so it is important to let him to see your client side scripts and style sheets.