I believe it is time to settle on a collation and force everyone too it.

I've fixed several clients databases already cause they've been getting errors such as this, cause the third party application they've installed used utf8_unicode_ci instead of utf8mb4_unicode_ci.

Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8mb4_general_ci,COERCIBLE) for operation '='

that is my entire argument for this. regards.

The "correct" location should be used so long as the site configuration is correct. For instance, some clients may be using utf8mb4 but not have the flag set in conf_global.php.

To address your feedback though, we should be using one collation globally.