Neglecting the Search engine optimization aspect
Imagine establishing a five-star hotel in a remote area which is inaccessible. Also, you do not take any step to design a way that the customers can reach the place. Only a mad person or a fool can sit and relax at the hotel waiting to receive visitors. Okay, maybe through magic. The same case applies here.
If you design a wooing website and then miss making it search engine friendly, you can only dream of high traffics. Regardless of whether you are using a free e-commerce website builder or a paid one, the first qualification should be SEO optimization abilities. Any builder promising you heaven without this ability should be your first discard.