I always see puzzles with “says grandpa”, “claims grandpa”, e.t.c. Why do we use grandpa?
Those questions are almost always written by a single user. I don't know why they like to make all their questions about "Grandpa", but it's a single person's quirk rather than a tradition on PSE as a whole.
I just saw this. Sorry for the late answer.
What can I say. This is a person very dear to me who is mostly as described. I just felt that introducing a character like Grandpa makes the puzzles interesting and sometimes humorous. His lateral thinking style is now familiar to many and now answers come very quickly.
I have received mostly positive reaction to Grandpa puzzzles and some on the site have come up with their own Grandpa puzzles too.
I certainly like to know if @Culver Kwan has some criticism of these puzzles.