Symphony.

So I run Gentoo, which among other things, means I know what and how things are installed on my server.

Trying to run the install tonight brought me to an unfortunate conclusion: only the mysql extension of PHP is supported.

Since it's obsolete, I generally don't compile it in, and without it, Symphony installer doesn't recognize the presence of my MySQL (actually MariaDB, but minimal difference) database service.

When I compile the extension back in, the installer ran to completion.

Is there some statement or rationale behind the choice?

It's something that's being looked at for the upcoming 2.4 release with the pdo work. I did build a replacement mysqli driver which is available in this gist that will most likely replace the default driver class in Symphony 2.4.

So at the end of the day, you are correct. At present Symphony only supports the mysql extension. The near future has a brighter prospect though :)

Excellent news! I'll look forward to that, and just keep building with mysql for now then.

There's also this commit, which merges that gist into the integration branch