Since you need to support versions of PHP that don't support the extensions that have parameterized queries.
> WordPress also works with PHP 5.2.4+ and MySQL 5.0+, but these versions have reached official End Of Life and as such may expose your site to security vulnerabilities
> PDO ships with PHP 5.1, and is available as a PECL extension for PHP 5.0
Unless you mean "hosts that disabled PDO"… I think they can safely be ignored.
Just checked, seems enabled by default on FreeBSD.
(Commented out in php.ini doesn't mean disabled — here it's enabled in separate files like /usr/local/etc/php/ext-30-pdo_mysql.ini)
MODX Revolution uses PDO exclusively, never had problems with it on any hosting service.
Commented out in php.ini does mean disabled - as in not enabled. PDO isn't enabled by default in FreeBSD you still need to install a separate package for PDO.
> Commented out in php.ini does mean disabled - as in not enabled.
Not necessarily, as I explained here: https://news.ycombinator.com/item?id=13761550
So while PDO may not be installed by a plain `apt-get install php5` or similar, I doubt the now deprecated `mysql` extension is installed by "default" in those scenarios either.
Edit: this approach also means that the PDO extension in php.ini will be commented, because its loaded by a package specific ini file e.g. /etc/php/7.0/fpm/conf.d/* which are generally symlinks to /etc/php/7.0/mods-available/
Here's a hint: Wordpress since v3.3 needs PHP 5.2+. MySQLi was added in PHP 5.0, PDO in 5.1
WordPress v3.3 was released in 2011.