How much do Content Management Systems (CMS), like WordPress, Drupal, Joomla!, play a part in search engine optimization (SEO)? Certainly bad site design (not clean urls, bad content, poor use of domain names, etc) in a CMS like Drupal is going to affect SEO (great tools used in a bad way idea). But do content management systems themselves lend to better SEO over others, if all the other good practices are done? And, how would mixing systems (ex, WordPress or Drupal blog supporting a Shopify site) affect SEO (again presuming all the other good SEO practices are followed)?
From a search engine point of view, there is no distinction between Drupal, WordPress, or Shopify. Before I get hit with “Wait a minute”, let me clarify. Search engines look at the HTML that is served back to them when they crawl links. They are not looking at the database behind the website and they are not looking at the admin page used to configure the site. What search engines are looking at is the HTML generated, or rendered, by the content management system.
For example: When using Drupal, you have to option of turning on clean URLS. You don't have to use clean URLS, but when you do, you get a URL that a human can understand (ex: http://example.com/products?page=38661&mod1=bnr_ant vs http://example.com/consulting/marketing). And, yes, clean URLs can help SEO.
Another example: Drupal, through its Pathauto module, will create meaningful URLs based off the page's title. For example, a page titled “10 Summer Activities For Your Kids” will automatically get a URL of http://example.com/10-summer-activities-for-your-kids . You don't have to use Pathauto but you should as it help make the page URL easy for people to read and remember.
Last example: Site maps help search engines understand what is on your site. While you can manually create (ug) a site map and submit it to Google or Bing, it is a task better suited to computers. Drupal's XML Sitemap module is a must have as it automatically generates and maintains the site map files and offers the ability to submit them to search engines.
Google or Bing are not so much interested in whether or not you use Drupal, all they really care about is the output of Drupal. But you need care about using Drupal, as it is a tool that makes easy the process of creating SEO friendly HTML and URLs.
Brief aside… Drupal is just a tool. It will provide the features and functionality needed to setup and run a website. It will not write great posts for you. That is still up to you. The number one thing you can do to influence any SEO rankings is have information that is well written, meaningful to the topic, and consistently created over time.