It hasn't been that way for a long time, but honestly, back in the day it was pretty close to true. Seemingly every site, and every poster on every message board had to do a "prank" . They were not the obvious satire bits you usually get today, but instead in depth hoaxs. It was bad, some would bread crumb days or weeks early, to make it seem more authentic, some would place them more obscurely so they wouldn't start to surface until after April 1st.
It made the internet a really unpleasant place.
Oh yeah it also lead to real news or announcements getting buried, or considered fake.