Problem:
There's a big discussion about how to deal with ellipsises at #44987: [policy] Use the UTF-8 ellipsis character instead of "..." in the user interface.
One thing that nobody seems to disagree with is that there's too many "..." styles comments and markup in Drupal. This turns simple sentences into unnecessarily vague sentences and does not seem like the best way to end a short list of items.
The policy discussion in the linked issue is long and complex and periodically creeps in scope massively.
It has been stated that "..." is missing from many languages other than English, so (ab)use of this in code can be a barrier to entry for developers who are not native English speakers.
Solution:
Delete every single "...", UTF-8 ellipsis character and &ellip; in Core that we can without changing the meaning of the text the character is situated in. If possible, complete the darn sentence properly with words that mean what they say and finish the sentence with a single ".", "?" or "!" character.
If for some reason we can't justify removing a "..." from somewhere, make a note of why and feed that back into the discussion at #44987: [policy] Use the UTF-8 ellipsis character instead of "..." in the user interface so that we can use it as an example to help form a solid policy there.