Ask HN: Why is the Linux community struggling to implement hibernation?

Today I have found out that hibernation is by default disabled in my Ubuntu 18.04 distribution. After this, I found this 11 month old post https://discourse.ubuntu.com/t/re-visiting-hibernate-on-ubun... where I realized that the Linux community does not seem to be able to implement a working implementation of hibernate. Is there any reason why this is a difficult problem? I would like to have an option in my OS like VM's have where everything that is currently running is saved on disk and can be resumed later without issues.