It was used, so still just there. But not anymore if they finally learned why safety in design philosophy is important by paying data corruption or service break. (anyway some people never learn…)

Safety is annoying. Safer system usually generate more errors to prevent accidental mistakes. Extremely safe system prohibits even booting up the product if it's not been properly configured. It simply has much more annoying safety net. If you care the safety, this kind of annoying errors are good sign to you. But if you're newbie, this is just a big obstacle, which makes stiff learning cube.

Really. We still see many people who hate to use safety belt. Because it's annoying. And everybody did before benefits of safety belt were widely known and accepted.

Also, number of users says nothing about how well the product works. Usually, cheapest product takes biggest user-base. MySQL is cheapest to start due to lack of safety. Search this thread for the name "natural219". And see why he chose MySQL over PostgreSQL. I believe that's why most people started MySQL at first.

And surprisingly, there're so many people really don't care data safety. (maybe not that much surprise. we always see those people in TV…)

The analogy I use: PostgreSQL makes you eat your vegetables.

Inertia, largely. Postgres is more scalable and has quite a few nonstandard additions that are insanely useful from time to time, but it's not always a drop-in MySQL replacement. If you're just writing something simple like a blog or CMS then you don't need the extra functionality.

Plus Wordpress has a hard requirement for MySQL, and like it or not a huge number of projects still use it as a framework.

but if its just a blog use mongo not mysql. non relational is a benefit and you have backups... postgres for real stuff.