The basic reason is that as WAMPServer can have multiple versions of PHP installed, you can use any of them from the CLI.
If you put ONE of the PHP versions on the PATH, when you want to use another version in a week/month/year from now, most people will forget that they put one on the PATH and then complain that they cannot use the version of PHP in the CLI that they want to.
So we suggest you do not put any version of PHP on the PATH.
I answered this on StackOverflow and provided a suggested bat file to use from the command line to temporarily add any version of PHP that may be installed in WAMPServer.
Please have a look at that---------------------------------------------------------------------------------------------
(Windows 10 Pro 64bit) (Wampserver 3.3.4 64bit) Aestan Tray Menu 3.2.5.4
<Apache versions MULTIPE> <PHP versions MULTIPLE> <MySQL Versions MULTIPLE>
<MariaDB versions MULTIPLE> <phpMyAdmin versions MULTIPLE> <MySQL Workbench 8.0.23>Read The Manuals Apache --
MySQL --
PHP --
phpMyAdminGet your Apache/MySQL/mariaDB/PHP ADDONs here from the
WAMPServer alternate Repo-X-X-X-
Backup your databases regularly Here is How dont regret it later! Yes even when developing -X-X-X-