Proxmox wasn’t considered because of the audience (leadership) and Proxmox’s perceived market (SMBs/homelabs). I couldn’t even get them to take Virtuozzo seriously, so Proxmox was entirely a non-starter, unfortunately.

FWIW, I use Proxmox at home. It’s a bit obtuse at times, but it runs like a champ on my N100-based NUCs.