I'd agree if POSIX provided something like an open() flag which made the changes visible atomically, but as it stands, the rename() idiom is the mainstream way of durable file writing, so it is commonly used. Practical example using busybox sed: (GNU sed detects this case and refuses to overwrite)

  / # stat /dev/null
    File: /dev/null
    Size: 0          Blocks: 0          IO Block: 4096   character special file
    ...
  / # sed -i 's/foo/bar/' /dev/null
  / # stat /dev/null
    File: /dev/null
    Size: 0          Blocks: 0          IO Block: 4096   regular empty file
    ...

It's the fundamental idiom of how to do atomic file replacement. The sever process had better be doing that over editing a text file in a way that could leave it invalid if the process OOMs mid edit, or another process is reading it while it's being written.