Feature summary:
I would like the line numbering implemented per T267911 to be enabled on all namespaces on all wikis, since I believe there are no issue reported for first wikis after T280027.
Use case(s):
Diffs show line number of changes. This useful indication is also requested for inline diff too per T347013.
However, there is no easy way to find the matching line in the editor, if you want to correct the changes.
Also, that would be much easier to quote an issuing line in talk pages, improving discussions about articles, especially for formatting/technical needs (wikifying).
Benefits:
All wikis would gain this nice feature, especially small wikis which are not aware they can request it.