If you have a business with a website and want to be visible when people search for your product or service, then yes!
SEO is what is deemed as “pull marketing” which means that it ‘pulls’ people to your site when they create a search on their phone or desktop computer. Your site needs to be where it can be seen.
To determine where your site is placed in relation to your cometitors it will be crawled and then indexed. To be indexed properly you must be properly optimised.