It's probably all because of PHP. Over 90% of PHP apps were built on Mysql (Wordpress, Drupal, Joomla). And you know, WP alone powers like half the websites on the internet. Sad reality.
This statistic is mentioned a lot, but it would be interesting to see a breakdown by amount of traffic on those sites. In these metrics thanks to the big web companies, the reach of Wordpress is much lower and other application frameworks are more predominant.
