As a java/OO developer first (web later), I got my start with databases by setting up a couple wordpress blogs, mostly simple UI stuff, but configuration and a few other cases got me into phpMyAdmin and MySQL. I wouldn't be surprised if this was the case for hundreds, or thousands of others. I don't -- or didn't -- mind MySQL so much because honestly it got the job done for those simple blogs and it was easy to get going. However I will say that now that I am surrounded by "production-level" projects, i.e. projects at work that affect millions of users and backends for my own mobile apps, I am extremely concerned about the performance, consistency, (over)complexity, and maintenance of my databases. I've gotten familiar with postgres, and while not fully understanding all its benefits over MySQL, it works great, feels sexy, and posts like this have pushed me to make the move.
Also, using frameworks like Ruby on Rails I feel abstracted far enough from the database level that the change really wasn't too difficult. It makes me wish I hadn't used MySQL in the first place, and started with SQLite because of its support on mobile devices, or Postgres.