I mostly agree with you. Its the "fabric" and tools that matter. In so far as this thread matters, I meant to say that VMware has a lot of great tools surrounding ESXi (which at least used to be the core of running VMs, may have changed)

In my opinion Proxmox does not have tooling like that.

So if I had written my comment better it would be what tooling and fabric these giants use and to what extent they share the tools and upgrades back to open source projects.