Hi Alex! Glad to have you here. This is indeed a popular idea. The biggest problem with it is privacy concerns. The best summary I've seen is at https://hillbrad.github.io/sri-addressable-caching/sri-addressable-caching.html. In particular if such a suggestion were implemented, any web page would be able to easily determine the browsing history of any user, similar to the old visited link color trick.
I don't know what the latest is on attempting to get around this, although that document suggests some ideas.
