Cybersecurity engineers and pentesters don't need Kali or Parrot. You don't need Proxmox to use LXC and KVM. You don't need OpenMediaVault to have Samba and NFS shares. You don't need Clonezilla to make use of the OCS toolkit. You don't need LMDE to have a Debian OS with Cinnamon and nonfree drivers installed, or Endeavour to have Arch with KDE Plasma.
But it's sure as shit good to have everything packed together and preconfigured by professionals.
Proxmox does add extended hardware support, as does Kali. Parrot enables necessary repos and kernel modifications for Red and Blue team workflows. I don’t know enough about DEs to speak about the others but those three don’t apply to the meme.