Why is Firebird not as popular as MySQL?
As you probably learned, Firebird is more mature, has more features, doesn't cost a dime and sure looks more enterprise ready. How come not so many people have heard about it?
The reasons are simple:
1. Firebird doesn't have a unique commercial entity that drives the development and earns money from it. There are companies, but none of them profit from selling Firebird licenses (as Firebird is completely free). They sell support, but the turnaround is much less.
Therefore, there is nobody to push the money into marketing and create a hype around the project. Similar problem plagues other open source projects like Postgres for example.
2. At the time of web server and web application boom, Firebird wasn't ready to be a web server database backend. As demand for data storage grew, people were demanding something easier and faster than Perl-parsed flat textual files. MySQL was simply in the right place at the right time. Soon, each ISP had PHP and MySQL support and the LAMP platform was conceded. As it often happens, those first on a new market quickly take it over, and it's really hard for others to take that marketshare away.