I don't know about other package managers, but please don't generalize dnf's behavior here to the others, because apt-get and dpkg would be just fine in this case. You can even disconnect from the ssh session and apt-get will continue until it is finished. In the worst case scenario you would call apt-get -f install and it would continue where it's left.
> There's not really a good solution _other_ than that,
Of course offline updates are valuable for the 0.001% scenarios but there are basic resiliency measures one should take while writing the basic building block of the distribution, before throwing in the towel and suggesting running it inside tmux or to use offline updates for everything.
This claim is not matched by my personal experience. Recovery is usually possible, but depending on the particulars may require non-trivial efforts.
I can't say much about that without seeing some examples. Of course it may not calculate&offer an ideal strategy or even outright choke if the system is put into a manually induced dependency hell, but that's a different scenario than resuming an interrupted process which was otherwise progressing OK.