Publishing in a journal is a long process that might take a lot of time (> 1 year), and is possibly involved of several phases (submit, re-submit, re-re-submit...)
As the time passes, things change. Specifically, new results appear.
What should one do with the new stuff that happens between resubmissions?
- Do one needs to cite / refer to papers that first appeared after the original date submission?
- Do one needs to update citations to papers that on the date of the original submission appeared only on arXiv, but now appear in a journal (those possibly slightly different than the original work cited in the original submission)?
EDIT: maybe one should wait for acceptance, and only then do the updates?