I’m talking about specifically about systems the size of Twitter. Arbitrary hard-coded rules are absolutely useful for smaller systems. I run a smaller system and such rules are useful and effective.
These are Twitter's filtered stream rules. They're accessible via the API to select from the global feed in real time. I don't have access to the firehose, of course, but my understanding is that it's an outgrowth of their internal systems. They have their own query language to filter Tweet and user parameters, semantic entity recognition, URL's etc.
https://developer.twitter.com/en/docs/twitter-api/tweets/fil...