MySQLi is not a new language, it’s been around for 11 years now according to this post from @felgall - Acessing Databases from PHP. MySQLi may be a bit different in the way it’s accessed than the older version, but it does not lack for information on how to use it out on the internet.
This might seem harsh, but in this instance, I’d actually argue that support on the site for a depreciated technology, should itself be depreciated. People are doing there best here to try and help out with best practice in what is a current technology, only to have that help turned down. At some point the help will begin to dry up if it’s not being heeded.
Here endeth the lesson…