From the user perspective, then, a SQLite backup doesn't seem materially less complicated than a postgres backup. I understood GP's comment to mean that it's easier to back up SQLite because it's just a file [which you can just copy].
It is just a file that you can copy when nobody is modifying data. In most simple cases you can just shut down the webserver for a minute to do database maintenance. Things that you already know how to do them. You don't have to remember any specific database commands for that. So the real difference is in the entry barrier.
I'm quite confident that if you can snapshot the vm/filesystem (eg VMware snapshot, or zfs snapshot) - you will have a working postgresql backup too...
