It's important to consider that an online service's poor behavior is amortized over it's user base (or all of the users who subscribe via the service's local copy of a given feed), so it _could_ be worse, if all those users were fetching the feed themselves.
It's also the case that a service wants to ensure they have the freshest copy or impatient users could bail somewhere else, or just do it themselves.
But, there's certainly an opportunity for a service to perform analysis on feeds to see the rate at which they're likely to have more content, as well as take cues from metadata.
At the end of the day, RSS isn't a protocol, and feed providers are just as wild west as consumers.
It's also the case that a service wants to ensure they have the freshest copy or impatient users could bail somewhere else, or just do it themselves.
But, there's certainly an opportunity for a service to perform analysis on feeds to see the rate at which they're likely to have more content, as well as take cues from metadata.
At the end of the day, RSS isn't a protocol, and feed providers are just as wild west as consumers.