It’s a failure when despite that the company goes bankrupt and the product stops being made. Consider actually reading the article. It’s the story of terrible business culture inside private equity firms that causes amazing products to keep disappearing. Being an amazing product makes you the target of these scumbags the very first time you stumble as a business. So you can tongue in cheek argue that is what causes you to fail.
I legitimately don’t understand the trendiness of proxmox given that vms are overkill compared to containers. If you are migrating from unraid you are likely already using the docker version of all your arr services so going and spinning up vms feels like a step backwards.
You can either use the exact same containers and use systemd to run them as raw services or use something like docker compose or dozens of other tools to orchestrate them. I use k8s but can’t recommend it with a straight face after taking down VMs for being overkill (very different kinds of overkill but still)