Apparently a lot of braindead RSS readers are written by even more braindead programmers. This quote from the CTO of Infoworld says it all:
Every hour, Infoworld “sees a massive surge of RSS newsreader activity” that “has all the characteristics of a distributed DoS attack.”
Attention idiotic RSS reader programmers: When a user says “check this site for updates once an hour,” they do not want you to check it on the hour, every hour! What they actually want is for you to wait an hour between successive queries.