Understand that in the hypothetical system we are discussing, there are something like 1-2 servers. In that case the "volume claim" is just "it's a file on the obvious filesystem" and does not actually need to be spelled out they way you need to spell it out in k8s. The file path you give in environment variables is where the most up-to-date version of the volume claim is. And that file is free to expand to hundreds of GB without bothering you.

Things get iffier when you start doing things like running multiple instances of something (maybe you're sticking two test environments for your developers), or suddenly you grew a bit or no longer fit on the server and start migrating around.

The complexity of PVCs in my experience isn't really that big compared to this, possibly lower, and I did stuff both ways.