Yes. SEO can help an ecommerce site to generate traffic and sales. Shoppers today use Google to find products and being in the top 5 search results is where you need to be to boost sales. We have boosted sites traffic and turnover by over 100% in six months.
Technically anyone can do SEO for their site but optimising a website so that it ranks on page one of Google for hundreds of keywords isn't easy without experience and SEO training.
You would need to learn about link building, meta data optimisation, crawl depths, anchor text optimisation and over optimisation, keyword density, indexing, page speed improvements, keyword intent, conversion tracking, server redirects and many other things.
An example of when that experience really counts is when perhaps you've optimised 10 keywords and they've all dropped in rankings despite your best efforts. But are they just about to bounce back? Or have your changes had a negative impact? Experience in SEO is important in being able to make sound decisions as to what to do next.
It's a matter of looking at keyword rankings over time and making smart decisions based on long term strategies.
It's for these reasons and more that we recommend hiring a specialist ecommerce SEO agency.