http://www.slate.com/articles/life/the_good_word/2013/07/ellipses_why_so_common_what_are_they_really_for.html

For those looking to learn the actual rules of ellipsis usage, the
Punctuation Guide provides a useful, if incomplete, primer. In more formal
writing, ellipses are often used to show omissions from within a piece of text;
in casual communications, they are used a zillion different ways. Individual
style guides offer differing rules regarding numerous elements of ellipsis
usage.

...

There were ellipses used in lieu of commas. Ellipses as question-mark
replacements. In some instances, it was ellipses instead of a single period at
the end of a statement, or 10 dots spanning two lines on my phone’s screen. What
a mess!