What makes WP so SEO friendly?

When you hear about SEO-friendliness of CMS it is essentially same as for static page – how URL looks and what gets into source of page.

Essentially WP is considered SEO-friendly because:

  1. It is easy to get pretty permalinks enabled and working

  2. There is large choice of themes and plugins, aimed at following recommended SEO guidelines (titles, meta tags, structure of headings, etc).

So this is not about WP being somehow unique. It is about it having tools (both native and extensions) to follow good practices for on-page SEO.