I do not know if there have already been discussions or if there even is a phabricator task, I, anyhow, could not find one and I have discussed this issue in real life with several fellow wikipedians.
Currently, echo notifications can be triggered if a page that a user created gets linked to from another page. I propose such notifications also to be triggered if the link is to a page on the specific user's watchlist. Granting this possibility would be fair because of the fact that the original creator of a page is in many cases not the author of its current content (page created as redirect or disambiguation, later made an article; article rewritten) or maybe (s)he is not who takes care of the page today (user left the wiki; has other interests...).
thanks in advance