PHP-FPM Configuration tutorial confusion

https://docs.01.org/clearlinux/latest/tutorials/php.html

This tutorial is causing me great confusion.

Why are we copying
/usr/share/defaults/php/php-fpm.conf
to
/etc/php.d/php-fpm.conf php.d dir…why this?

Why create php.d dir inside /etc ?

When full defaults path is:
/usr/share/defaults/php/

The php directory in default location has this structure and files within:

%3Ausr%3Ashare%3Adefaults%3Aphp

I just don’t get why not just copy
php
/usr/share/defaults/php/

to /etc

Then we have exactly the same directory with files and sub dir’s files in etc as the default location, we then use the conf files in etc for customisation.

What’s the purpose of dir php.d ???

It has been demonstrated that php conf file =php.ini, this resides in the php dir

It has been demonstrated that php-fpm conf file = php-fpm.conf', this also resides in php` dir

It has been demonstrated that some directives (like adding extensions) added in php-fpm conf file = php-fpm.conf, do NOT have any affect on php-fpm and that for some bizarre reason know one seems to have clear cut answers to.

It has been shown that some of the php.ini directives DO in fact have control over php-fpm configuration and actually php.ini is required in-addition to php-fpm.conf to define specific directives that php-fpm.conf ignores.

Seems I need to reach out to PHP core developers to get some hard facts on all this confusion because there’s noting in the PHP documentation that provides any certainty.