Workflow

Some panels have a script to update a Smart Liquify layer when you've changed stuff beneath it.

I've not checked that out in detail and if you can do that with an action too... I suspect it's just replacing what's inside the SO with a Merge Visible from Below. So that's another helper in such workflow.

As mentioned by @Conrad_C and @Chuck Uebele Smart Objects and other non-destructive techniques exist (and have for a while) so could you describe the process in question in some meaningful manner? 

There are several workflows of that type. One that I use is to use File > Place Linked to place raw files as Smart Object layers. They are referenced to the original files, not copied into the Photoshop document. As Smart Object layers, they are preserved as raw data, so if the metadata edits for the original raw files are changed in another application such as Camera Raw or Lightroom Classic, Photoshop pulls in those changes and updates the Smart Object layers of those raw files in Photoshop — a nondestructive and flexible workflow.

In addition, because the raw file layers are Smart Objects, filters applied to those layers are nondestructive Smart Filters, so they can be revised at any time. And of course those layers can have masks and use opacity, blending modes, and Blend If, for fully reversible nondestructive compositing of raw files.

Add in the other nondestructive Photoshop features like adjustment layers, and you can take nondestructive editing pretty far.

Yes, you can pretty much construct a workflow to be nondestructive. Some things in PS might require you to use a destructive method, but for those instances, you can make a duplicate if the layer. It's very helpful to be able to go back and edit something.