This is actually to combat a 'best script' from dominating all the delegates feeds. Consider this:
1. Feed sources (e.g. exchanges, which are limited in number, less than 101) are made readily available for delegates through individual scripts. These scripts' sole purpose is to query whatever server the source comes from, and return a number (or set of numbers: price, bid, ask, order book, volume, etc.). Each currency pair at each feed source would have a script. The hash of each script is stored on the blockchain. These can be updated. (By delegate votes? delegate-voted developers?)
2. a 'feed maintenance' script which periodically tests all the scripts and through logic, and determines if any of the exchanges are being manipulated and/or giving false results. The hash of this script is stored on the blockchain, can be updated etc.
3. a 'feed distribution' script which through logic and quality checks (possibly using more than just the price, e.g. volume, spread) determines the best way to weigh the feeds. The hash of this script is stored on the blockchain, can be updated etc.
4. The delegate can choose a percentage of how much to trust this script, against his own manual feeds or private custom script, 0% - 100%. This number is public Using the 'feed maintenance' script, 'feed distribution' script, and optionally his own feeds, the delegate now is serving all the feeds required.
The current system promotes laziness in the delegates, as all they have to do is download the latest and greatest feed script and fire away. And I don't blame them, that's probably the best way to do things right now. It just makes for weak feed security, due to lack of diversity.
Besides of easy maintenance for delegates, the purpose of this is maintainable transparency, where shareholders can see everything that is happening and can feel more secure in the system.