The issue of tracking entities that quote your resource is not really the size of a problem that demands this much answer.
IIRC, the original design included a large number of other features that became nonsensical as modern conventions for information arrived:
- We do not require licensing or micropayment for quoting text or speech. The www follows free-speech by default, and tools must be built on top to restrict things. (Among many reasons why not: There is no permanent trust-able entity for enforcement)
- There is a vastly larger usage of linking than quote usage (links jump but also embed)
- Commercial licensing of text, images and video is still required but the infrastructure to enforce it has to constantly differentiate by usage and intent (satire, education), not mere presence or absence. (YouTube's big review process...)
- There is no permanent barrier to building a free side-channel for information that would otherwise be licensed. (P2P File Sharing, etc)