Gary Lawrence Murphy writes about the problem of aggregators accessing RSS feeds and the resultant increase in network traffic that it causes for the feed provider:
If your feed works, if you are successful in attracting subscriptions on a global scale, if you do it right, you are doomed.
As friends tell friends, as links lead to visits which lead to subscribers, the snowball rolls on towards that day like last Friday. RSS may have the potential to be a saver on bandwidth, but when you are getting hit once an hour or more by thousands of sites, 24,000 extra hits ads up, and it’s all the worse when so many are using broken clients that ignore the caching rules.
This is where centralised aggregators can play a role.